As I mentioned earlier, I've been playing with WF.  When debugging in Visual Studio, a program running a workflow pretty much uses 99% of CPU the whole time.  I thought that was pretty scary, especially since I had alot of Delay activities in my workflow.  Well, not to worry, running the .EXE outside of devenv gives you what you expect, a very well-behaved program.

I suspect it has to do with the sweet debugging stuff that's built into the workflow designer surface.  You can add breakpoints to activities.  It's pretty cool, despite crashing on a regular basis.  Hopefully, they'll fix this before RTM.