Here's a bit of surprise, Seesmic, developers of one of the most popular desktop Twitter clients, has just demoed their upcoming app for Windows Phone 7.
Now considered to be a launch-partner by Microsoft (see also Foursquare and Netflix), Seesmic's Twitter app look quite classy. In addition, they have a Sliverlight plugin-platform/SDK which will allow external applications easy integration e.g. Bing maps and encourages 3rd parties to interact with their program with ease. That means we should see tight integration with Seesmic and other apps like RSS readers to quickly share links; smart idea.
This will be the first Windows Phone client from Seesmic who already have ones for Android and Blackberry. Between Seesmic and Twikini, looks like early-adopters will have their Twitter needs covered by the best in the biz.
Edit: turns out this was actually posted two months ago and we missed it, so not exactly breaking but still it was news to us at least ;-)
Edit 2: Not for nothing, but our timing was good. Seesmic just announced the availability of Seesmic Desktop 2 (preview), now based on...you guessed it Silverlight and featuring plugins for Foursquare, Buzz and Facebook.