The design templates are XAML-based templates for building Windows Phone Applications.

These templates make it possible for you to copy paste XAML to easily create common Windows Phone UI layouts, and since the templates follow the Windows, you get a “metro” experience with zero effort.

Some available useful resources you should look as:

Watch Microsoft Blend team introduce and demo here

Silverlight UI Design for Windows Phone 7 interaction at codeplex

Offline Windows Phone 7 Training Kit download

Hoang Nhut Nguyen
Skype: hoangnhut.nguyen