Dina Mehta is missing BlogHer (something about several feet of rain on the runway in Bombay), and she's written a piece about what blogs have done for her in the past three years in BlogHer in Spirit. I have to agree with a number of her sentiments, but most critically "My blog has become my social network."
Blogging has significantly expanded the people I can rely upon as friends and resources. I've been a moderately active participant on mailing lists and various online fora. These have created friendships for me as well. But blogging has brought people to me that I don't believe I would have found via these mechanisms. The (online) world is much larger than any of those groups, and blogging in public opens my thinking process to anyone who might stop by. Of course, there is the question of making that happen, but search engines and friend-of-a-friend references have brought me more contacts than I could ever imagine. I've met grad students, fellow consultants and even some potential paying clients. And most importantly, I've had fun in all these conversations.