Windows Phone 7 is without a doubt the most exciting mobile platform for developers and if you are a .net developer, especially if you’re a Silverlight developer, then you should download the beta of the Windows Phone 7 Developer Tools today.
Windows Phone 7 website: http://www.windowsphone7.com/
Follow Windows Phone 7 on twitter: https://twitter.com/windowsphone
Follow Windows Phone 7 on facebook: http://www.facebook.com/windowsphone
Windows Phone 7 TechEd online sessions: http://www.msteched.com/Tracks/WindowsPhone