Suw blogs about Yet Another Pointless Social Network (YAPSN) issues. Interesting post and something that I've been observing myself. How can you get people to keep coming back to a Social Network Service like Orkut or Friendster once the initial fun of creating the network is gone? I think that a lot of the YAPSNs focus too much on the size of your network. When Orkut was publishing the "most networked" top 10, everyone was running to have the biggest network. It was a game. I now have 1001 "friends". Whoopie! This is incredibly useless data for me. Sending a message to all of them would be spam. I really don't have much use for Orkut's network at this point other than to fiddle around and look at pictures when I'm bored. (Some of the communities on Orkut are interesting so I drop in from time to time.)
I personally find LinkedIn useful. (Not just because Reid is my friend.) LinkedIn is not about fun. It's about work. There is really no way to have too much fun on LinkedIn, so my network is very utilitarian and I'm mostly connected to only people I actually know and would write a reference for. This is a useful data set. You'd think LinkedIn wouldn't be viral since it's not that much fun, but it's growing faster than any of the social network services.
But as Suw points out, social networking is a natural byproduct of doing things like photo sharing and music listening. I think that the way for many of these YAPSNs to survive will be to integrate with external sites such as last.fm and flickr. However, once you've grown your social network to 1001 friends, there really isn't any way to unpollute your data so at least for me, I can't imagine how Orkut could become more useful to me. I guess I could eBay my Orkut account and start again. ;-P