We announced at PDC today that we're making some significant advances in diagnostics tool support for CLR v4! In particular, we've been investing heavily in improving our support for production diagnostics scenarios over the past couple years. I'm excited that we're finally able to start talking about it!
Here's a quick list of some of the things we're doing - stay tuned here, Dave's blog and Mike's blog for more details. Also feel free to ask questions about our strategy and specific plans for new features on our forum (of course we still have a few things we're not ready to talk about yet). Of course, all of the features below are only available when targetting a process that is running inside version 4 of the CLR.
That's the overview of the main CLR v4 features that affect diagnostics. Of course there are also lots of other great things coming in CLR v4 and the rest of .NET Fx 4.0.