Just in case you needed any more Twitter in your life (I'm getting to the point where I really don't), enter the PlayXpert Twitter widget, part of the PlayXpert gaming toolset, a free Windows application that you can download to run alongside your PC games (very similar to Xfire and that type of application). It's a little bloaty if all you want to do is run Twitter alongside WoW, but unfortunately, that functionality will never be available in an addon, as addons can't interact with any other outside sites.
The poor man's solution here is to just run WoW in windowed mode and have your Twitter browser or client open right next to it -- you don't need a big application if you really need to be connected at all times. But if you want to livetweet your raid without sacrificing screen space to windowed mode, PlayXpert is one way to do it. It'll even do some autotwittering for you if you want.
And of course if you're on Twitter already, don't forget to follow our WoW Insider Twitter account. We've already hit our goal of over 9,000 followers (and yes, a video version of the podcast is coming soon), but we're constantly throwing out little pieces of news, discussion and even some giveaways over there, so follow us if you're interested.