For a long time, sending a bug or suggestion to Microsoft has been a bit of a challenge. For the .NET Beta, we've introduced the MSDN Feedback Center.
I will ask you to bear with us, as we're just getting up to speed on this. You may get answers that aren't as good as you'd like, or we may miss some issues. If you get into a situation where the right thing doesn't happen, feel free to drop me a line, and I'll see what I can do.
This is for beta1 only right now, but we'll expand as time goes on.