As we were hard at work creating PFX, we had a sister team of great talent working with us every step of the way. Their job? To do to Visual Studio 2010 what PFX did to .NET 4.0, by substantially improving the development experience for parallel programming on Windows. This includes both diagnostics & debugging, as well as profiling.
Daniel Moth, the program manager for a lot of the IDE features, just wrote up a comprehensive blog post on the new tasks window:
Parallel Tasks - new Visual Studio 2010 debugger window
The new window gives you a view into all of the tasks in your process, their statuses, and where they are running:

Because both TPL and PLINQ use tasks for execution, it supports both quite nicely. And it has (consistent!) support for both .NET and C++ tasks. The parallel stacks window is also an impressive new feature, and I'm guessing Daniel will also cover that in the coming weeks. Keep your eyes peeled. If all goes well, you'll even get to try them out first-hand, once Beta1 is available.
And if that weren't enough to entice you to visit his blog, check out this nasty machine that Daniel uses to run his kitchen appliances:

Oh, the insanity. I am thinking Task Manager will need revising in Windows 8.