We've been playing with Tweetie 2 for the iPhone for a bit and have to say really makes Twittering easy. Somehow atebits has added a lot of features without taking away the simplicity of the original app.
One small catch: If you've already downloaded Tweetie, you'll have to buy it again. (It is worth the upgrade) Get Tweetie 2 here -$2.99 (App Store Link).
