Vista SP1 kills activation in Fusion/Bootcamp installs
In case you're unaware, apparently Vista SP1 has killed VMWare Tools's ability to manage activations, because SP1 introduces significant changes in Windows activation. I learned about this the hard way when I installed Vista Ultimate from my bootcamp partition--it seemed to activate just fine in Fusion, but then when I booted natively from the bootcamp partition, it was asking for activation. It (re-)activated there just fine, but then when I booted into Fusion, it's asking for activation again!
Over at the VMWare forums, a company rep (Jim Gill) acknowledges the issue and states they're working on it. In the meantime, the only workaround is to uninstall SP1. Here is one of the relevant threads:
http://communities.vmware.com/message/897252#897252