It is not totally obious how to unlock your WP7 device for development. The first step is of course to sign up for the development program at http://create.msdn.com. But then? I had the exact same experience as this guy:
http://www.pitorque.de/MisterGoodcat/post/Unlocking-a-Windows-Phone-7-device-for-development.aspx
So together with the SDK a small activation program was installed, “Windows Phone Developer Registration”. Start it and login to active your device!
