After months of anticipation, Windows Phone 7 has now been officially launched in the US and in Europe.

Microsoft first announced WP7 at the Mobile World Congress 2010 and according to Microsoft it is now available on 60 carriers in 30 countries. The first device manufacturers to launch WP7 phones include Dell, Samsung, LG and HTC.

In this post, I will shortly summarize the differences between WP7 and earlier Windows Mobile platforms, focusing on the app/browser/video features.

The first important fact is that WP7 is not backward compatible with Windows Mobile 6.5 applications. WP7 application development will be based on Silverlight, XNA, and the .NET Compact Framework 4 only. Also, Adobe has announced that Flash Player 10.1 will be released for WP7 but no release date has been made public yet.

Microsoft has put a lot of effort into creating an "app store" for WP7, for more information visit this site.

The standard browser is a new version of Internet Explorer Mobile with a rendering engine that is "halfway between IE7 and IE8". A key difference is that there is no support for RTSP links, so if your mobile web page has hard-coded RTSP links they need to be updated. There is no support for HTML5 or Webkit extensions.

Interestingly, if you click on a video link on the YouTube mobile web site the phone will launch a YouTube application and play the video in the app (the Apple iPhone does the same thing). For most people, the preferred behavior would be to play the video in the native video player and then return to the web page.

Based on our tests WP7 has good support for video, including HD quality H264 streams. Other supported formats include VC-1 and Windows Media Video.

Our favorite WP7 device is the HTC HD7 (aka HTC Surround in the US). The HD7 has a 4.3" screen with 480 x 800 resolution, a 1GHz CPU, surround sound and a convenient kickstand, perfect when you want to watch a full episode of Boardwalk Empire.

We are happy to announce that ThirdPresence can deliver high-quality video streams, including HD, to all the WP7 devices currently on the market.