We have Jive set up a group area foe eachh upgrade. We create a document that list the "special" items, customizations, and changes to the base configuration tha need to get migrate. When we start testing, our QA group creates a document that list the bug, priority, and status.
I find the more process, checklist, and timeline info that is documented and shared, the better.
Combination of wikis, spreadsheets and for user testing, a discussion thread to make it easy to participate and share experiences from the test.