From my point of view, the network is the data and to make them useful we need applications to run against it. OpenBC and LinkedIn are pretty good business networking tools and this is definitely a start. I get multiple link requests from LinkedIn each week already. Orkut has been a big disappointment — I just logged in for the first time this year, and found that nothing had changed.
If you know me and want an invite to any of those networks that I listed above, just ask.
So what is my ultimate social network? I should be able to run my own applications across my network, with appropriate protection and privacy. For example, I’d like to be able to plot my friends on a map, so that I can make sure to catch up with them if I happen to visit a particular city. This is an ideal application for a web service.