[Silverlight] "AG_E_RUNTIME_MANAGED_ACTIVATION" = You don't have Silverlight 1.1 installed

I'm thinking a better error message might be in order when folks try to view Silverlight 1.1 content with managed code and only have Silverlight 1.0 installed, but for now this is what you get  (obviously the last three lines will vary depending on the actual XAML content):

Silverlight error message
ErrorCode: 2251
ErrorType: ParserError
Message: AG_E_RUNTIME_MANAGED_ACTIVATION
XamlFile: Page.xaml
Line: 9
Position: 9

Solution: Download the Silverlight 1.1 Alpha Plugin.