I recently upgraded to Mac OS X 10.6.8 and already had Parallels version 6 build 12090. After upgrading OS, performance is poor, Dock icons won't show, operation is slow. Troubleshooting says to upgrade parallels to build 12092 but I can't figure how to do that without downloading version 6 as a trial copy. (Since I already have purchased it, I am not going to do it again).
If you have already activated and registered PD6 build 12090, then installing "trial" version of 12092 left you activated and registered.