...and yet every permutation of "Brian Willis" is taken. Many of which are spam accounts which twitter seems completely uninterested in killing off.
Besides their developer-relations problem, namespace pollution and stagnation is a big problem for Twitter going forward. Who wants to join and use a service when the closest thing they can get to their desired username is a second-class moniker like @ffffirst_last1 or @L4stF1rst88 ?? I've heard this complaint from several of my friends who were late to the Twitter scene. The name availability issue is the main reason I think app.net has any chance of succeeding.