No, this will be legit. I know Fox has been in the works to do a SImpsons movie for awhile now, and if I am not mistaken, it will mark the end of the Simpsons on TV. Last I had heard, it would be a 2007 release, and would follow the final episode of the Simpsons, capping off a rediculous run of what, 20 years? I bet it will be fantastic, and much like the South Park movie where they go where they couldn't go before.
pat