Can you remember when Android was full of mess and didn’t have any design guidelines at all? That changed when http://developer.android.com was launched and it became the sole central source for Android 4.0 design framework. A good step that Google made.
Microsoft thankfully has created their own website dedicated in teaching and promoting Windows Phone app development. The website has walkthrough videos and resources to help aspiring designers and developers create their own app. I think it would be better if they add an updated downloadable “stencil” templates (icons, layouts, etc) as well. If you’re interested in WP app development,go ahead and check out http://www.generationapp.com.