Over at the still-going Apps review marathon, we've touched on three Twitter apps that bring the service to iPhone 2.0, with varying degrees of success. Twitterific's version for the iPhone is as good as their OS X desktop client with a beautiful interface, and it's free if you don't mind the ads (US$10 to make them go away).
By comparison, the other main free app Twittelator is a bit more buggy (can't connect to server errors, etc) and is far less pretty. Neither can notify you from the background, though, so for timely updates a lot of people will still be using good ol' SMS to let everyone know when dishes are being washed, meals eaten, etc. One thing: Twitteriffic still not quite as good as the free jailbreak app Twinkle, which allows you to filter tweets by people who are within a certain distance of yourself. [App Review Marathon]