I had previously Googled up a Facebook app for Twitter after seeing the developers service that FB offered, and the only thing I found was some half finished application which didn't seem to do much. Now, only a few days after my initial discovery of the incomplete plugin, Twitter advertises its official Facebook plugin on the profile page of each member.
The plugin is just an extension of the Twitter interface onto the Facebook page, where you enter your username and password for your Twitter account, and some runoff of the standard Twitter home home page, with a list of recent updates and input box to post some more. It somewhat disappointing that the Twitter status doesn't overwrite the Facebook status, but I don't think that the FB API even supports that yet. Will we see that in another version?
In the end, this plugin isn't really revolutionary, but it's fun to known that you can interlink all your social networking sites, showing all the other geeks and regular people how little life you really have.