After using m.twitter.com, and playing with a bunch of Twitter client Apps on the iPhone, I finally found something usable in TwitterFon.
TwitterFon, is just a simple app that lets you see your friends timelines, post your tweets/replies/DMs, and it even has a built in browser so you can view links in tweets, and add links to your tweets. It also allows you to view your friends mini profile, and their timeline.
If you are looking for a more advanced iPhone Twitter client, check out Twittelator.
You can follow me on Twitter at: Twitter.com/mzampino