From a design point of view a nice thing about Windows Phone is that it brings with it a whole set of design guidelines which are referred to as “Metro”.
Microsoft has developed a sets of guides to how controls are supposed to look and establishes a set of criteria that your applications should meet if they are to be “good looking applications.”
For further details see the Metro style document, you can find the style guide here: http://msdn.microsoft.com/en-us/library/hh202915.aspx
This is well worth a look if you want to publish your programs in the Marketplace, where your potential customers will have certain expectations of how things should look and work.
Additionally the following interviews are a GREAT virtual guest lecture for teaching UI and UX course attendees on concept and theories of design.
On way-finding graphics
On mobile audio
On light & space in architecture