Here is one more nice design discussion from O'Reilly Network about building type-safe arrays and hashtables on top of the type-unsafe implementations provided by the framework.
All the solutions evaluated have some issues, and generic types are mentioned as a solution.
For other angles on type safety and genericity:
- O'Caml is a safe and strongly typed language with polymorphic inferred types.
- Microsoft Research has a .NET Generics project. Apparently, the next version of C# may include Generics, as mentioned in this GotDotNet article on future C# features. This article also mentions Iterators, Anonymous methods and Partial types.
- Here is a partial .NET implementation of O'Caml, called F#, by Microsoft Research.