As promised, Twitter today officially launched Twitter for iPhone (free, App Store. Apple's platform is one of the last modern platforms to get an official Twitter client but is getting a significantly upgraded version of Tweetie 2 following the buyout of atebits. It adds a unified search that includes updates, users and Top Tweets at the same time. Users no longer need to be signed into an account just to read and can sign up from within the app itself.
