Twitter is a micro-blogging messaging system with over 5 million users and growing - check it out at www.twitter.com
Anyway I have set up a Twitter group at http://twittgroups.com/join/guildwars
Basically if you join the group then any time someone sends a tweet to #guildwars you'll receive it, and you can use the group yourself.
My thinking is that if we got enough Guild Wars players using Twitter, it would make it easy for grouping up and such as you could contact GW players offline in real time to arrange for things in game.
My Twitter name is bi11iard - feel free to add me there if you like.
Setting Up Guild Wars Group on Twitter
Billiard