It's a good news to have the MSDN documents for WEC 2013, there are more and more information to point out what's the difference and how to work out the new OS design for WEC 2013, also, you can check out what's the difference between WEC 7 and WEC 2013.

Catalog Changes from Compact 7 to Compact 2013 (Compact 2013)

http://msdn.microsoft.com/en-us/library/jj919252.aspx

What's New (Compact 2013)

http://msdn.microsoft.com/en-us/library/gg154234.aspx

enjoy~

-Zebra,