Clean, light, easy—three adjectives that aptly describe the official Twitter app for the Windows Phone 7. This nicely rounds out their mobile app presence for the coming year, and it’s a solid display as well. We defer to the Twitter blog for the announcement du jour,

There is a new addition to our mobile family: Twitter for Windows Phone. This Twitter client is available now for all Windows Phone 7 devices. We want you to be able to get Tweets quickly and easily, no matter what device you’re using, and the clean design of the Windows Phone platform is particularly great for this.

As with our other mobile clients, Twitter for Windows Phone includes all of the features that you’d expect from Twitter – your timeline, suggested users, messages, lists, and a great way to explore Twitter without even logging in. You can sign up for an account right from the app as well. The app is really fast, and we think you’ll enjoy the experience.

The app makes extensive use of a Windows Phone 7 UI innovation called “pivots,” which are a multi-screen interface accessible through swiping directionally at the screen. A user looking at their twitter feed can highlight a tweet, then swipe—this causes the application to generate a new screen in that direction and slide it in accessing details, maps, retweet, reply… The Windows Phone interface design of pivots allows for a giant landscape of virtual real-estate which helps increase the virtual size of the desktop, while enabling the user to still work through the small aperture of a mobile screen.

Twitter has once again produced a lovely, simple-to-use application with a lot of room to grow on.

Now 3^rd party application designers like TweetDeck and others will have to show they can extend and deliver; but customers won’t need to worry about being left in the dust when it comes to basic support from the Twitter people themselves.