When Twitter swallowed Tweetie maker Atebits, they declared that an official Twitter client - a la Android's - was on its way. You'll be happy to hear that Twitter has barely changed the iPhone's best Twitter app, except where it counts: Price.
The app is currently showing up for Tweetie users as an update, but should be available here any second. It's very familiar: Aside from a new icon and start screen, this is Tweetie 2.
The only functional change I've noticed is the new search screen, which includes a trending topics rundown - some of which can be accessed even if you're not logged into a Twitter account. (The idea being that you can glean news from Twitter the second you download the app, and continue to do so without a user account. Twitter lurking, I'll call it.) Other than that, all of Tweetie's best features are here, including the should-be-standard-on-everything pull-down refresh, tweet swiping (for options like reply and retweet), and the super-clean interface. Also present are a few of its annoying quirks, one of which causes every direct message you've ever received to appear as unread. Also, the app doesn't include push notifications - you'll have to use an app like Boxcar for that.
Still, Tweetie was a deal at $4, and it's a no-brainer for free. Every other Twitter app maker now has two choices: to step up their game, or to die. [Twitter]