We know there are already quite a few Twitter apps for Windows Phone 7, but you can always have more, right? Birdsong is a new one that brings some features you may have been waiting for. This one’s got configurable timelines, so you can add saved searches, or lists as separate timelines. It’s got integrated picture viewing and Twitpic image uploading. It nicely supports the global Windows Phone 7 themes. And here’s the big one, it’s got threaded conversation view for mentions and direct messages! You’ve been looking for that feature, haven’t you?