Expression Blend and Silverlight
The only version of Expression Blend that has been fully released is v1 (available free to students through DreamSpark). However v1 does not support the creation of Silverlight applications (hence no Silverlight project type). In fact v1 is used to create WPF (3.0) applications only.
There is a page on the Expression Web site that outlines Blend versioning but it is not all that easy to find.