The importance of the Acuff-Rose case, even though segments of the case were remanded for further findings was that the Supreme Court reached the unequivocal conclusion that a parody falls within the scope of the fair-use defense.
I like how that site, noted at the bottom of the page, in bold lettering, not legal advice contact whomever for legal advice. Decide for yourselves whether this is advertising or genuine.
Yup, the Fair Use Act. However, I'm sure with SOPA and PIPA one of the 22 agents trained to carry out the domain nuking duties will conveniently overlook Fair Use.
If they had to be funny, then all of those "Scary Movie" / "Epic Movie" etc mainstream films would be sued into oblivion.
I find it funny how the porn parodies sometimes refer to themselves as the "Official" parody, as if there is some governing body making sure that there is just approved parody material out there.