The rumors about Microsoft totally cutting the compatibility cord with Windows Phone 7 were true.
Charlie Kindel, Microsoft Partner Group Program Manager for the Windows Phone Application Platform & Developer Experience, in a March 4 blog post, acknowledged that existing Windows Mobile apps won't be able to run on Windows Phone 7 devices. From his post:
"To enable the fantastic user experiences you’ve seen in the Windows Phone 7 Series demos so far we’ve had to break from the past.To deliver what developers expect in the developer platform we’ve had to change how phone apps were written. One result of this is previous Windows mobile applications will not run on Windows Phone 7 Series."
Kindel said Microsoft will continue to support phone makers who rolled out Windows Mobile 6.5 phones "for many years to come," meaning "it’s not as though one line ends as soon as the other begins."
Kindel also confirmed that Silverlight and XNA will be key to the Windows Phone 7 development platform. .Net developers will find "your skills and much of your code will move forward," he said.
Microsoft will detail more of its tools and plans for Windows Phone 7 application and game development at the Mix 10 conference, which kicks off on March 15. Microsoft is expected to have more to say about Visual Studio 10 support for Windows Phone 7 at that time.