Downloaded and installed Q1 2009 and there is still a problem in Blend 2.
Description - The Name "RadGridView" does not exist in the namespace http://schemas.telerik.com/2008/xaml/presentation
DLL - Telerik.Windows.Controls.GridView
Version - 2009.1.312.35
I dragged the control onto the window via the VS2008 toolbox, opened my project in expressions blend 2, and received this error.