We have experimented with this ourselves and our solution was to write a small companion application that wraps White (http://white.codeplex.com/) and SpecFlow (http://www.specflow.org/) to run our tests. We build and deploy this seperately.
In terms of the workflow, we just have a number of Jenkins slaves with different labels and use the Matrix project and the vsphere plugin to run our test executable. We then revert the build slave back to a base snapshot before the next test run.
