In my previous project, I have helped our QA setting up automated UI testing in Selenium 2.0. We initially had some trouble setting it up, but it seemed usable.
Besides stresstesting our webservices we haven't really done any automatic testing on our applications. So you got me curious as well.
Take a look at Mendix and Beyond these guys have some ideas on that and I know that in one of their projects they have a dedicated test team that uses one of the HP products to automatically test Mendix apps.