If you haven't already, read David Lee King's post about Web 2.0 and friending. It might be hard to swallow at first, but he's absolutely right.
His main point:
When your organization decides, say, to create a Facebook page … who are you trying to connect with? Me? I don’t live in your neighborhood. Another library on the other side of the world? They’re not going to use your services.
He's right in that libraries aren't implementing Library 2.0 tools to connect with other libraries - we need to focus on connecting with our patrons. Any library service (be it a newsletter, a storytime, a flickr collection, or an rss feed) should be directed to the patrons. Those are the people (we hope) who will benefit from it.
Friending other libraries is safe and tempting, but is slightly counterproductive (we don't want it to look like these are library-only tools). But I also agree with David (and commenters) in that it's important to connect with other librarians professionally, and to keep up with what other libraries are doing - there are a lot of good ideas out there that we can adapt for our own libraries.
Hmm. I'm guilty of this myself, but I'm going to keep in mind moving forward.