Living in Washington, DC with a lot of other people who are over the age of 30 and still single, it's not as hard as I anticipated it would be, actually. The key is to have reasons to bring people together. I'm in a karaoke club, and a programming meetup, and several other things, and my social life is pretty healthy as a result.

With parenthood in the mix, you have to get really aggressive about scheduling, but it's still not impossible.