Wesner Moise seems to have a few issues with a few things in the CLR, particularly weak references. He then goes on to call Smalltalk a "language of the past":

I had a lot of radical ideas that I didn’t mention, mostly involving features from various academic languages that unlikely to come in the next few years. I firmly believe that the new advances in languages will borrow heavily from languages of the past such as Lisp and Smalltalk. Already, we have seen the advent of garbage collection, closures and iterators in C#. Languages will also become more declarative over time.  

Smalltalk is hardly a language of the past - look here, for instance, and download it. It's also amusing to see him describe things that Smalltalk and Lisp have supported for decades as "radical ideas". Maybe the radical idea would be to drop the language that doesn't support 3 decade old "radical" ideas and use one that already does...

And obtw - VisualWorks supports weak collections. Too "radical" for the CLr, I suppose...