I’ve just found a great set of podcasts with Tim Heuer about Silverlight 4. It is not new now but for sure it is very interesiting. Here is the ToC
Overview: What are the core things to know about Silverlight 4? How does it compare to Silverlight 3?
Controls: What are the new controls in Silverlight 4? What new support is there for controls?
Out Of Browser: How do elevated privileges work? What are toast notifications? How can Html be hosted in an Out Of Browser application?
Printing and Webcam: How do the new printing/webcam APIs work?
WPF vs Silverlight: With Silverlight 4, there are fewer differences between Silverlight and WPF. How do we decide which technology to use?
Text Improvements: What are the big text and international improvements in Silverlight 4?
Networking: How do the networking changes in 4 impact Silverlight developers? What new things can they do?
Databinding: How does the new Dependency Object support help designers?
Download podcast pack