[jopt]

I think you're taking a huge leap in your reasoning. Sure, I want lots of people I know on the network. But beyond the roughly 200 of those, I don't care if the network has a hundred thousand users or a hundred million.

Before facebook, social networks could provide a lot of value by saturating small demographics. Example: If all Swedish teenagers are on playahead.se and can all talk to each other there, they don't gain much from network expansion. The reason those networks need to grow beyond the clique where they're successful is that their business model can't sustain itself on a small number of paying users.

If app.net saturates the demographic of "people who care enough about Twitter's new API to chance $50 away," I could talk to 50% of my Twitter circle even if the total number of users on app.net is only 1% of Twitter's.

[sirclueless]

Most people I know couldn't give two hoots about talking to random people on the internet, even interesting random people. All they care about is their friends (and maybe famous/notable people). If your social network contains < 100,000 people, chances are it doesn't contain many friends, so most people will discount it. Now, us techies are used to a degree of anonymity, and are used to interacting with people we haven't met, so I don't think it is impossible that app.net will be successful in that demographic. I think it is akin to Netflix: some people just want to watch a movie, it doesn't really matter which one so long as it is a decent one; these people might like Netflix. But others only really care about that specific movie their friend said was good; chances are Netflix doesn't stream it, and they will be disappointed.