Twitter, the social 'micro-blogging' service that allows users to post short, 140 character updates (or "tweets"), has been very popular amongst members of our IT department. It allows users to 'follow' each other to stay up to date with what they are up to. Updates from your friends can be delivered via the Twitter website, instant messaging, SMS, or via desktop software. It tends to be a very rapid form of communication, with most people seeing updates within minutes of them being published.
I have set up a Twitter account for Wessex Archaeology. All of our blogs are configured to send a quick 'tweet' whenever new content is posted, so that followers of WA on Twitter can be alerted of new announcements within minutes.