One thing I would very much like to have is an automated mechanism to update the labs cluster VM wikis reliably to some known version of MW for those configurations. Right now I think it would be best to update those nightly from Jenkins rather than after each commit, or whatever. (I've discussed this with Antoine somewhat)
Ultimately this serves two purposes: for one thing, it offers a chance to bring in the global testing community at will for ongoing testing of new features. For another thing, in the longer term I would like to add some builds downhill from the deploy-to-labs-cluster builds that would run a suite of cross-browser UI tests against the labs cluster environments nightly.
I've put up a QA/testing status page to track this and other items.