[This is one of a couple of essays that first appeared in BUSTed magazine. (If you don't read it, why not? There are vendors and you can even subscribe for free.) I'm going to post them here for those of you who may not have seen them.]
Facebook is designed around being able to grab data about you and sell it to people. Not giving accurate data decreases the value of the data Facebook accumulates, and hence Facebook forbids it. In particular, they'll delete accounts that don't correspond to real people. (It's not clear how determinedly they search for such accounts. I see a lot of people who create accounts for their pets so they can get ahead in FarmVille.)
Second Life is different. You can be who you'd like to be. You can reveal as little or as much about your "real life" self as you wish, and for someone else to reveal such information about you violates the Second Life Terms of Service.
The ability to change what you don't like about your body—height, weight, proportions, skin, even gender—appeals strongly to a lot of people, I'm sure especially to those who don't conform to the general public's notions of beauty. "On the Internet, nobody knows you're a dog" is even more true of Second Life. (Ouch! I have to wonder whether the original cartoonist meant to allude to "dog" in the sense of "ugly person".) Plain women can know what it's like to be beautiful, and may even be at an advantage in SL compared with those who in real life have gotten by on their looks. The elderly can feel young again for a while. Handicapped people can spend time in a world where they can walk, run, and even fly. Those with gender dysphoria but who could never "pass" in real life can experience at least a little of life with their appearance finally matching their true selves. At least before voice the deaf, stutterers, and others were all on a par with everyone else, and strong accents or inability to produce or distinguish all the phonemes of a non-native language were not an impediment to communication.
That in turn gives rise to the stereotype of the fat old man in the basement in Second Life as a younger person. (Just in case we want to refer to him again, let's use the acronym: FOMITB.) "If you don't use voice/go on webcam so I can hear/see you, you're a FOMITB." We are still ourselves in Second Life, and some people only traffic in the counterfeit coin of feeling good about themselves by putting others down. (David Letterman's career is built on it. As a fan you are in on the joke and can join in the smugly superior contempt in which he holds the average people he interviews.) Second Life takes away some of that. (Admittedly, it adds some, too; vide SL Fashion Police and What the Fug?)
In Second Life, I'm very tall and leggy—as much as I can make myself with the stock Second Life avatar—and I'm towards the high end of the breast size distribution. I'm far from the tip of the tail, as a look at Laurana's Cuties, a Second Life group of women who agree to always maintain an avatar bustline of at least one hundred inches, will show. [UPDATE: I am a proud member of Laurana's Cuties, but I am barely over the lower bound.] Even so, I'm still well out in the distribution... and the author of "The Long Tail" is right. Here are some comments on some of my self-portraits on flickr:
"....And, gods, you're beautiful."
"Great picture, and what an awesome figure you have."
"Exquisite, sensual, and erotic."
(There are less complimentary comments as well, but that's largely my own doing. As an experiment, I submitted myself to What the Fug? I wanted to know what they'd say about modestly dressed but large prim breasts. I found out, all right.)
That's heady stuff for anyone who's never been complimented on appearance, and a strong motivation to continue in Second Life. So to some extent, Second Life may be selecting for those the stereotypers bash. Should that make anyone not participate? Of course not, and I hope Linden Lab doesn't throw any residents under the figurative bus to pander to the stereotypers. I guess we'll have to wait and see.
UPDATE: You're right. It should be "Whom Does Second Life Attract?", but I'll leave it as is.