Twitter is testing out a new mobile interface at the company announced just minutes ago and it really is a must-see. Beautiful design and some unique functionality are built on top of the company's own API.

It's a relatively simple way to interact with Twitter but below are three key features that weren't available on Twitter's mobile interface before. Two features, lists and saved searches, are missing so far - and that's enough to be a deal-breaker for this reviewer.

  1. View what you're replying to when you reply.

    The new reply view displays the tweet that's the subject of your reply below the message composition box. All Twitter apps should do this!

  2. Threaded DMs

    You can see the history of Direct Messages between you and any user whose profile page you're on. It's similar to how Tweetie 2 does it and it's pretty nice. Oddly, there's no way to view all your most recent DMs though. That's something that will probably be fixed soon.

  3. Mobile Fail Whale

    That's right - now you can get the beloved Fail Whale, Twitter's error message, on your phone. It's fun the first time. We'll see how it feels after repeated appearances.

  4. Two Missing Features and One Dream Unfulfilled

    There are no support for Twitter Lists in this interface. Twitter without groups of some kind is a cluttered mess if you have a lot of people you're following. This new interface is going to be best suited to people who make casual use of Twitter.

    There's no access to your saved searches, on of the nicest things about the web interface. There is access to trending topics, though. That's further evidence that this is intended to be a "fun" mobile interface. As such, it's great.

    Finally, there's no utilization of the new Geolocation API. It's been a week already and no one has changed our lives with this API yet!

    All in all, it's a great improvement to the mobile site - but it isn't going to replace the Tweetdeck or Tweetie iPhone apps on my phone.