Here’s a list of resources to begin with the development of native applications for Windows Phone 7. I will update it along the way, maybe I will categorize them when it becomes necessary.
http://msdn.microsoft.com/en-us/library/ff626516(VS.92).aspx The class library reference for Windows Phone SDK. It contains only namespaces specific to WP7. At the bottom of the page you will find the links to Silverlight, XNA class reference pages which include not only documentation for Silverlight for Windows Phone but also all others platforms. You can check the support of WP at the bottom of the page. For example on the List<T> page you can see that it’s supported by the mobile framework :
In the documentation section you will also find about the differences between runtimes support : http://msdn.microsoft.com/en-us/library/dd470087(v=VS.95).aspx
http://social.msdn.microsoft.com/Forums/en/windowsphone7series/ The forum is very active, more than Stackoverflow.com maybe because there’s not a lot of developers yet and not a lot of development on the platform either. This thread in particular can be interesting to find samples.
If you like videos, this session of 12 videos on Channel 9 about WP7 is very effective : http://channel9.msdn.com/posts/egibson/Windows-Phone-7-Jump-Start-Session-1-of-12-Introduction/ I didn’t watch the ones about XNA but the others can be useful even if you are already a Silverlight developer.
Windows Phone has a very particular UI (code-named “Metro”), so you can’t really bring your desktop or web UI knowledge. The UI design guide is very helpful to get an overview of all the controls style, there’s a page listing the styles used by the OS and available to applications. The videos from the Design Days are also a good way to grasp the UI philosophy.
The execution model is also very particular because it’s a mobile platform : battery, signal and CPU/GPU access are big constraints. This page is a good read to understand the activation/deactivation process (tombstoned application). The performance tips are very important (video on the tips).
Check http://phone.codeplex.com/ to get the Pivot and Panorama controls.