Channel 9 has a brilliant video series that will help aspiring Windows Phone 7 developers get started. It starts with the basics and would help you to work your way up so in a few hours, you will know enough to build simple WP7 applications.
The series contains 64 videos spread over a four-day curriculum. The development is done using C#, although VB.NET source code is also available. The series is presented by Bob Tabor from www.LearnVisualStudio.net,.