SimplyTweet is getting better and better. This latest update, v1.5 (pending approval) adds swipe-to-reveal shortcuts, replying to multiple people (reply all), Posterous integration (multiple photo support), multiple photo support for TwitPic, unread counts, and many more little touches. Can't wait for it to be approved!
Get it now and you can upgrade to v1.5 when it is approved. Upgrades are free.