Somehow I doubt it, but an article in the London Telegraph today is hinting at it.
Keep in mind, however, that for The Telegraph, anything having to do with the Catholic Church or (gasp!) the Pope is considered evil, bad, wicked, pernicious, etc. So in my opinion, this is nothing more than an opportunity to bash President Bush.
That said, if Mr. Bush were to convert, I'd welcome it! He's proven to be a fairly lousy politician, but I always thought he was effective when it came to testifying about his faith in Christ.