All of this does appear to stem from the guest list at the TomKat 'wedding'
The news from today is that Jim and J-Lo are both officially denying it - quite a few articles listed here on the subject.
Carrey, Jim (Actor):
"And some speak out, such as Jim Carrey and his good friend Nicholas Cage, with some crazy stunts. One time Carrey delighted in calling CC one day and getting them all in a tizzy at a big name calling them to ask about Scientology. Except Carrey wanted to sign up for the OT3 course. He had all these "things" on his body, he said, and he wanted to get rid of them. The execs freaked a bit, saying that he had to do other things first. No, no, Carrey said, I'll pay for all those. Get me on that body thetan course, that's the one for me! (I mean, can't you just imagine a Jim Carrey routine on body thetans?)" - Robert Vaughn Young.
The Scientology Experience
Jim Carrey and buddies Nicolas Cage and Crispin Glover decided to check out the Church of Scientology in Hollywood. Carrey said, "I tell you, that was a scene. The three of us walked in, and these Scientology people thought they'd died and gone to heaven. Crispin said, 'We'd like to, ah...look at, uh, the training film.' And they said, 'Oh, yes, come right this way.' They led us into this little theater and they showed us the Scientology promotional film and I watched Karen Black and different celebrities with this glazed look in their eyes talking about how Scientology saved their lives, saying things like 'I'm not workin', but I'm happy.' It was completely frightening!!!"
According to my WHO magazine Will Smith was also at the wedding and he has publically declined Tom Cruise's attempts to introduce him to Scientology.