Our test cycles are large, and take quite a bit of time, so we assign projects to each major release version of our software.
To manage this I have a project which contains a master list of testcases, which we copy into a project to build up the list of tests which need to be executed.
It would be really handy to have a way to show the history of where test cases have been moved / copied from or to inside the suite, and therefore be able to build a multiple version history of tests.