UPDATED!
Just ahead of the Build conference, the Silverlight team is pushing out a new version of Silverlight 5 that is a Release Candidate (RC). This version is meant to help you upgrade your projects from the Silverlight 5 Beta version and get ready for the actual release. This release does not include a “GoLive” license but is considered to be feature complete. There are a number of new features since the Beta including:
You can get it from the Silverlight.NET site.
UPDATE: Note you cannot use Blend with Silverlight 5 RC. This should be solved fairly soon, but if you need to continue to use Blend with your Silverlight 5 projects, wait to install the RC until a new version of Blend is available.