A Silverlight 5 beta will be available in the first half of next year, and the final release will ship in the second half of 2011.
Hardware video decodeTrickplayRemote control supportBetter Databinding and MVVMWCF and RIA Services: Silverlight 5 now includes WS-Trust support. Improved text clarityBetter printing supportOut of browser supportBetter and faster drawing Automated testing toolsSmaller downloadFaster performance