Bill has posted up about aliasing syntax in VB.NET and some of the features he would like to see. One interesting suggestion was about importing namespaces with assembly versions. Currently in MSIL it is impossible to do this because while you specify the source assembly name, you don’t specify the version – thats in the manifest.
Bottom line, too much would have to change in the CLR to support this code executing in the one AppDomain (you can have different versions of the same assembly provided that they are loaded into seperate AppDomains).