This thread is a bit odd. Hmm, I always was under the impression that Ben did something special since he felt it was important to tell Vader that he would gain more power after death. Then, when he disappeared, Vader investigated to ensure that it wasn't a trick. This implies that it wasn't meant to be a common technique among Jedi. Seriously, Darth Vader had to have killed many Jedi up until that point. That's all according to the original movie though, and not the stuff that George Lucas threw around after that.