Are there any mature samples of WP7 code available either on codeplex or somewhere?

Question

I am looking for some advanced samples of windows phone 7 that use expression blend for UI design and VS 2010 for app development that talks to services etc. and probably uses some frameworks.

Answer 1

There are a number of good tutorials at Kirupa, some of which also explain Blend. Another Blend specific tutorials is this article. You can also download some WP7 design templates that comply to the Metro UI guidelines over at CodePlex.

You can also download code samples over at MSDN which has the Weather Forecast sample showing how to use web services.

Regarding frameworks, you could look into MVVM. The MVVM Light Toolkit is quite popular regarding the implementation of MVVM in Silverlight applications. (Articles and tutorials further down the page)

There's a huge resource list here, although it covers all sorts of aspects, not just advanced samples.

A WP7 book is also being written, which you can download the preview version of here.