This one is a bit difficult for me. I've resisted a Facebook account because of some of the difficulties that have been associated with it. However, after creating an account, I sent a message to a friend I haven't talked to in quite a while and looked at some pictures from an event I recently attended. I've seen how teachers are using Facebook as a class blog/website, and feel that with some pretty firmly established guidelines it could be lots of fun and helpful for students. However, I'm still a bit cautious about it and honestly don't know how much I personally will really use it.
Now about Twitter --- It can accomplish amazing events; look at how it's being used in the aftermath of the Iranian elections. And, I can see it's value for some applications in a classroom. However, after spending some time on it, reading a variety of "tweets", and noticing that no one in my phone directory is listed on Twitter, at this point I'm not a fan. I just don't think I'll use it. I've even checked with young people I know, and the majority say they would rather use IM or email; several of them say Twitter's become too much sharing of unnecessary details; they implied that it's technological TMI.
This was not one of my favorite things.