When I took 2 hours to play with Selenium, I was blown away. Together with the Selenium recorder (now Selenium IDE) you have testing dynamite in your hands. Usually deploying a website takes a lot of regression testing which doesn't happen too often. Using Selenium you can run a good sanity test within 5 minutes.
I find it hard to say, but in my opinion the days of jWebUnit as a functional/integration test suite are numbered. Perhaps one release to fix the outstanding bugs, upgrade the libraries, and then move over to the new world: Selenium.