I don't know about anywhere else in the world but Twitter seems to be going through the roof here in the UK. You go on the radio and someone is talking about twitter or they are getting comments from it, TV shows are talking about, newspapers etc.
I've been using twitter since about July 08 and have found it a great way to communicate but since Christmas I have been on it a lot more as more people join. http://www.twitter.com/alex_pearce
I'm not going to claim any of this work but you can see how to add Twitter through you content editor webpart over at a post by the guys at End User SharePoint