Quick note, guys. As far as I know, Silverlight has support for the basic datatypes. It's the pre-.NET 2.0 collections that it does not support anymore.
You can see a mapping of the old to the new here. As Gradiation said, this will make PureMVC for .NET 1.0 obsolete (if PureMVC moves forward with this deprecation). However, shouldn't PureMVC for Silverlight be a different branch, due to the different goals of Silverlight vs desktop/server .NET?
Sorry if I jumped the gun on anything; just trying to clarify as I read it. My two cents
-Michael