This is old news, since it first surfaced nearly a month ago, but with Comic Con just around the corner, it seems like a good time to ponder what, exactly, caused the reported ban. Prowse, it seems, wanted to play the role again in the prequel trilogy, but that wasn't in the cards. He told The Sun in 2005 that he didn't like Return of the Jedi "because of the Ewoks" and, as far as The Phantom Menace was concerned, he "felt they lost the plot with all the strange characters and convoluted story." At his official site (and evidently in his autobiography, Straight From the Force's Mouth), Prowse says Jedi was the worst film experience he'd ever had.
Prowse announced recently that he's made a full recovery from prostate cancer and has a lineup of appearances scheduled through the end of the year. Just don't look for him to be hugging George Lucas any time soon.