CLR PUM Jason Zander has posted information about the availability of debug symbols for Beta 2. If you haven't used the symbol server before in your debugging, this post is a good introduction to getting started doing that. Check it out here:
Public Symbols for Beta 2 Now Posted
...The symbols posted are what we call "Public Symbols". They contain the function names and offset inside of the DLL's, but no line number or local variable mapping information. To see the difference, check out these two call stacks I did on regasm first without and then with symbols...