A fun topic! I've tried out Second Life, but my current online gaming home is World of Warcraft. I'm very much a casual player (if I'm lucky, I might manage 5-8 hours in an average week, including some weekend time) but I enjoy it for several reasons.
1) I get to spend time actually doing things (as opposed to talking/exchanging email) with friends who aren't local to me anymore. This is good. I like talking to them, but sometimes you want to do something together, which is tricky when they're in Boston or the DC area, and you're in Minnesota.
2) There are days when it's really good to sit down, and figure out the optimal way to get through a quest or a goal, and then do it. One thing I like is that often going and playing for an hour or two will help me get unstuck on some other problem - my brain gets a chance to spin and process while I'm playing and not paying attention to the other issue.
3) I'm totally and completely fascinated by the apparatus of play, and by the integration of different parts of the game/player goals, etc. More on that below.
4) It's a gorgeous game environment: you can get everything from barren lands complete with lions who stalk their prey to dense rain forests, to ice covered mountains, and with all sorts of ecology. The game is divided into different 'zones' which can have weather, different kinds of challenges. I deeply enjoy this part, oddly enough.
If you're not familiar with MMORPGS, they essentially involve thousands of players interacting in a virtual world. Some settings (like Second Life) involve all sorts of individual projects, or even companies, designed by players. (There are things like Egyptian temple reconstructions, libraries, stores, and all sorts of geography).
In a game like WoW (the common abbreviation), the game world is designed by game programmers (which usually means the graphic quality is very high), and they also design many game events. For example, there are quests, where someone will have a job for you to do - this might be finding something, delivering a message, or killing wolves, bears, or other monsters in order to help keep an area safe, or to get enough materials to make something that's needed by the quest giver.
Characters begin at level 1, and get new abilities and skills as they increase in level (through experience gained by doing quests and fighting things). They also have different classes - my favorite, for example, seems to be priests, who are good at healing (and therefore very popular for grouping), but who can also fight evil and monsters quite effectively. Different classes have different play styles, too, so a warrior will hit things with a sword in melee combat, a hunter has a pet that can attack, while a priest or mage will stand back and use spells.
On a more complex level, there are interactions between different groups of characters. You can cooperate with others in a small group, chat with friends in a guild or team up for a multi-person quest in a dungeon or instance (a separate area of the game usually with specific goals and even harder challenges). Finally you can fight against others in other factions (in WoW, these are the Alliance and the Horde: both have pros and cons, and they're not good vs evil as much as different paths and goals.)
Finally, many MMORPGs have crafts or other skills you can improve (and sell the results). For example, you can make things out of cloth, leather, or metal. You can mine for ore, gather herbs, skin beasts. You can do things (enchantments, jewels) that give you additional game benefits. And beyond all of this, there is a thriving game economy (with cross-overs into the real-world economy, at this point.) Making money off the in-game auction house occupies some people entirely by itself - and is a fascinating micro-economy in action.
Information about the game:
The part that totally intrigues me, however, has to do with how people find information about the game. There is the game website, of course - but this is only a tiny part of what's out there. Sites like WoWWiki provide detailed information about quests, equipment, and other details (where to find this quest goal, what to answer to that question to get a particular result, why you might prefer one area to level your character in over another.)
The one that fascinates me even more, though, are sites like WoWInsider, which has a series of blog columns (by different authors) on many facets of the game. Not only are there predictable ones - new game content as it's introduced, ideas on playing a character class better or more effectively, how to group or run a guild better, but there are even craft projects and cooking recipes (replicating in-game objects and food.) These are merely the tip of the iceberg: there are significant numbers of sites with leveling guides, class guides, equipment advice, and other information, not to mention forums for discussion.
Now, why are these fascinating?
1) Significant numbers of people are writing and reading in-depth material about something, using critical thinking skills, and learning to write clear documentation that others can follow. I don't know about anyone else, but I think that's good for society.
2) Some of the projects and recipes would do very well for a generic library craft project night with very minimal editing (or not - there are 10 million WoW players worldwide, about half of those in the US and Europe. Some of them probably are near any given library.)
3) There are a lot of extremely good (and useful) uses of Web 2.0 tools being used for these games. Wikis are an obvious example - but you can see, just in the two sets I linked to above - the use of photosharing, blogging. Many players use Voice over IP technology to talk voice while playing together.
4) Other related skills. Instance runs need between 5 and 40 people - the management skills needed to organise a guild or a larger instance run are substantial. The more I talk to teenagers who are participating in guilds, or even in smaller groups, the more I see an awareness of teamwork, long-term goal setting, ability to deal with delayed gratification, and ability to compromise for the good of the shared goal. I think those are also great things for everyone to be learning - but that they're especially promising for the teenagers I work with, who easily take these skills into summer jobs, group school projects, or extracurricular activities.
Different types of games:
The actual blog prompt for this Thing is about comparing Second Life and an MMORPG. I've tried Second Life, but it's not as comfortable for me.
I have to admit that the graphics quality of WoW (and other games I've played a little in the past, including EverQuest, City of Heroes, and Star Wars: Galaxies) has spoiled me: I find the roughness of Second Life a little hard on the eyes (especially on my home computer, which is not a high-end graphics machine.)
But I also find it a little harder without a goal: I tend to prefer to do my discussion in-depth, and I don't enjoy purely social chat with people unless I know them fairly well, or unless it's task-oriented (Someone asking for help on IM chat is fine. Random conversation about what I'm doing with a stranger? I've probably got other stuff I want to be doing.) This means I tend to do actual conversations in a text-focused medium (email, LiveJournal, blogs, Usenet, etc.)
In a MMORPG, I've got other things I'm doing while I'm chatting (my own quests, enjoying the scenery, making progress towards my goals) that can happen generally independently of where I am in the game: it isn't purely a social or discussion situation.
That said, I can see great benefits for Second Life for use for meeting space for people who are geographically distant, or where you've got some other pre-managed task (lecture, presentation, etc.) The problem with this, of course, is timing. I can play WoW at any time I happen to be free (and only need to arrange similar play times for things we want to do directly together). To attend a presentation in Second Life, I need to be able to be on at the same time, which in my life (and others) tends to be a bit tricky.
I definitely see these kinds of virtual environments becoming more and more a part of the general public life in the future - they're engaging, they give tools and resources not always physically possible, and they can involve some amazing interactions. I can definitely see their uses for distance education, team communication, and project work.
There are, of course, some concerns (harassment or even simple lack of physical exercise), but there are generally ways to mitigate these. The more worrisome one is the lack of digital access: Second Life has some fairly significant computer requirements, and not all older computers will run it well, for example.
The other one is the sheer amount of time: there's a fair learning curve to making things in Second Life, or to learning the game in a MMORPG. It then takes additional time to make connections and build friendships, to keep up with the information about the game, and so on. Since the days aren't getting more than 24 hours in them, that does mean other interests tend to disappear somewhere.