Starting from TP 2.3 development we are using Selenium for acceptance/regression testing (more regression than acceptance for now). I should say that Selenium is very cool tool for web applications. It is very easy to learn and very powerful tool. It works with AJAX without any problems.
So we are going to integrate Selenium with TargetProcess. It is possible to run Selenium tests and send results to server (via POST request). Server (TargetProcess) may handle the request and update statuses of Test Cases. It is required to bind test cases to selenium tests, but I don't think there will be major problems.
Not sure when this will be implemented, but it is required even for us so I think we will give Selenium integration a priority and implement in TP 2.4 or TP 2.5.