There are a growing number of games (or, more accurately, game-like chatrooms and social networking sites) that are all about meeting people and flaunting what passes for your sense of fashion.
The one that's been getting the most attention recently is, obviously, Home on the Playstation III. But there are lots, literally dozens of them. All of them are passably similar: Home is simply more graphically advanced. An older one that still gets a lot of press is Second Life, although it... is a little different.
The vast majority of the chatrooms and social networking sites are bubbles. They can't keep their audiences, period. There are lots of theories, generally accompanied by handwaving about niches and saying, "if we only had more users, we could hit critical mass..." Hrm. Wrong. Let's talk about why they really fail.
I'm going to come at this as if entertainment and play all spring from the same basic system, so I'm going to refer to these pieces of software as if they were games. You can certainly argue that they're not supposed to be games. In which case, you've just explained right there why they always fail. So, as if they were games.
Playing a game can be thought of as exploring an evolving terrain. How well you can explore and interact with various parts of the terrain changes based on your capabilities. In most MMORPGs, you can actually go to any map you'd like, but you'll get your butt kicked if you're not the right level. Putting together and leveling a team is the fun part - advancing your ability to explore and shape the terrain, and in the process exploring the "terrain" of the level and equipment system.
Terrain doesn't always mean physical terrain, of course: in a MMORPG, you shape terrain by killing monsters and collecting loot. Solitaire has a terrain built out of cards, where you explore by stacking cards in specific ways. Changing and exploring the terrain of cards is, again, the focus point.
I could argue it for any game, but I'm going to presume it's fairly clear by now: games are about exploring and changing terrain.
Now, let's take a look at MySpace. Met with a polished but cluttered front page, I click "comedy". I'm faced with another cluttered page filled with links to what are presumably intended to be comedic pages. I'll click on Michael Gelbart. Voila, video, a couple of other links, and some extra information. I'll be nice and presume the video clip is not his best work.
The point is, I'm now exploring terrain. At whatever speed I please, in whatever way I please. And, if Gelbart pleases me, I can look for related links. Even better, I can always watch for more Gelbart in the future. The terrain evolves. I could send Gelbart fan mail, or post to his comments, or whatever else I wanted, and I might even get a response, a shoutout, a friend, or a linkback. Of course, his "MySpace level" is 23,214, whereas mine is zero, so it might be an iffy thing to try. Might want to level up some first by integrating into the terrain of the game.
It may sound like I'm stretching, but I'm not. Although the methods are different, being on MySpace has a lot of underlying similarities to killing trolls in WoW or driving cars over hookers in GTAIII. I doubt it was designed that way, but enough mutations and you'll end up with one that's viable...
Now, 95+% of the wannabee-MySpaces fall short. Their terrain isn't deep enough, or doesn't react enough, or isn't permanent enough, or some similar problem.
In SecondLife, the terrain is deep, but it's nonreactive. The vast majority of the socialization must be done live, which is too intensive and irritating for the bandwidth available (text and emotes). Sure, it has its place, but that place isn't in long-term viability. This is a problem a lot of 3D chat rooms have. I haven't done anything with Home on the PSIII, but I wouldn't be scared to bet fifty that they suffer from this problem, just from seeing their ads and previews.
On the other hand, most "social networking" sites go another direction, where the terrain is so sparse that it's simply not interesting to explore. "It's supposed to be functional!" Functional is something users want to come back to, not forget.
So what's the secret?
Terrain that is interesting enough to make exploring it entertaining. Terrain that reacts, but at the player's preferred speed. Terrain which varies as to how responsive it is. And complex rules linking it all together. (In most cases, the complex rules are people's personalities.)
A system of personal webpages enhanced with friends lists, content stacks (blogs, vids, pics), and forums is basically ideal for this. Going 3D requires... some interesting changes. Changes I haven't seen happen, yet.
I'm sure you can be successful without this, but it will be because you have other terrain which does get explored in this way. For example, SecondLife's social scene is tenuous, but it has a fairly complex economy, crafting system, and real terrain that interacts in ways like I explained above. Their "social"ness is painfully bad chatroom standard, but they have other terrain to explore.
Now I'm probably going to be on the top twenty for Michael Gelbart searches. That's Google terrain, there. Not quite as juicy, but the same basic idea.