Initially when I started TestCase I just needed some testing facility for my Prototype based code and I was not satisfied with the scriptaculous testing way. But now, it becomes obvious to me that the project is not uses Prototype much in really and I seems need to test some MooTools based code, and then some people are too excited about jQuery.
So, I've thought that it will good for us all to make the TestCase project framework independent and put all the frameworks related stuffs in plugins or something like that.
That's it. Watch out, TestCase 2.0 is on its way to every mind ;)