I will attempt to answer some of the questions/comments on this trail:
WebSphere Studio Application Developer is essentially the combination of VAJ and WebSphere Studio. It is now file-based (VAJ is repository based), allows you to swap out which JDK you use and is otherwise more flexible than VAJ/WebSphere studio were.
Why get certified in an IDE? Basically for the same reason that one would get certified in anything. If you have no work experience, a certification may give you some credibility. If you do have work experience, certification may help to set you apart from others without certification. Also, certifications, like degrees, are a lot more "provable" than work experience; unless, of course you give tests to the people you are interviewing. Even then, the certified person might be better off, as he is used to taking tests.
I don't view IDE certification any more or less valuable than certification in anything else. It is just proof that you've mastered a product (or at least mastered enough of it to pass a specific
test).