Found this interesting podcast from Chad Stoller of Three Minds @ Organic. While this isn't a super complicated look at social media, it does have some of the basics of whats working/not working, where social media may be going, and what companies should do to measure ROI.
Twitter, which I'm currently experimenting with, is one of the things Chad talks about. He sees it basically as an RSS feed for his friends' lives. Even though, he may not have spoken to someone in 6 weeks, Twitter allows him to feel like he knows what's going on without actually being in contact with the person. I can see how this can be a time-saver and a good thing, but I can also see how this can be a bad thing. If you can't make time to talk to someone every so often, chances are they aren't that good of a friend.
Other than the Twitter stuff, see below for a couple other good quotes. For more, check out the podcast.
"If you're going to be innovative with your media plan, be innovative with your metrics."
"It's not always about the volume, it's about the quality of the participation."