The overall best iPhone Twitter app, Tweetie, is about to seriously leapfrog everybody else with version 2, with everything you could want—offline reading—and way, way more.
The extent of its offline powers alone is impressive: Not only is there caching, but it remembers your exact place in the app, and you can bookmark, follow block or Instapaper while offline. All of it's just synced when you go online.
There's also drafts manager, live filtering, push notifications (down to the specific user level) and this is killer—the ability to link up people you follow to contacts in your Address Book, plus a dropdown to pick people to @reply. There's a ton more, which is why it doesn't seem so bad that it's gonna cost another $US3, instead of being a free upgrade. But yeah, every other Twitter app developer's job sounds like it just got a lot harder. [Atebits, TechCrunchMashable]