There's an excellent conversation with Jonathan Yarmis at PCWorld entitled How Businesses Can Benefit From Social Networking. Excellent read -- I especially like how they talk about avoiding the "kumbaya effect". 

Another high point is that many businesses initially jump in to social networking for their external site, but find out it's much more valuable on internal (intranet/extranet) pages. It makes sense, really -- on your public site you'd mainly use the tools for marketing, with limited initial impact. However, when you leverage such tools for internal knowledge share you get a lot more ROI.

We had a meeting recently with the CTO of Ektron. He showed us how he managed his European sales team using the Ektron social networking tools. It was pretty impressive how naturally and easily information flowed.

Anyhow, check out the article -- good stuff!