Last week it was reported that the Silverlight 5 Release candidate was available, but it did not include support for Expression Blend. This week Microsoft has announced that the release of Expression Blend Preview for Silverlight 5 is ready to be downloaded.
This release includes the ability to create Silverlight 5 projects such as Silverlight 5 SketchFlow projects, and is installed along with Expression Blend 4. This new version is limited to Silverlight 5 projects, and is not backwards compatible.