Does anyone who's already upgraded see any improvements in idle CPU usage and/or battery life on a laptop?
Yes, there are improvements in CPU usage. When Windows is idle, Parallels consumes around 15% (out of 200%) of CPU on my MacBook and when paused between 2 and 3%. It was possible to get these values with the previous version but only by disabling sound input and possibly USB support. Now with both USB support and sound input enabled, I get resonable CPU usage. There seem to be some applications that still cause high CPU usage when idle though. 40tude Dialog is one of them. Whenver I've got 40tude running and idle, Parallels uses 38% of the CPU for some reason I can't explain.