Lots of people access Twitter on their phones via our good ol’ mobile website, and trusty 'm' has been delivering tweets faithfully. However, 'm' doesn't fully feel like Twitter, and could probably do a bit more things for you.
You can view the new version of the mobile site with your phone's browser at mobile.twitter.com. The site resembles the Twitter homepage you'd see on the web with tabs for "home," "mentions," "favs," and "messages," as well as reply, retweet, and favorite options. I also read that there's a mobile version of the fail whale, though I have yet to see it on my own.