Go download the Silverlight 4 RC! Runtime (PC, Mac) Silverlight 4 Tools for Visual Studio 2010 Expression Blend 4 Beta Silverlight Toolkit WCF RIA Services Just a few of my favorite new SL4 RC features since the Beta: Full screen pinning (watch videos full screen while typing in a different window, on a different monitor.  wahoo for multi-tasking!) Rich text formatting spring loading (be able to hit bold and just watch it work) WebCam preview (see previews of the web cam in the config dialog) Binding support in VisualStates (use databinding in your state storyboards) Navigation loader refresh (support refreshing …