Actually this might be a bigger case than we all realize. For those who create content, and constantly refer to contemporary and popular culture it is important to know what's fair use, public domain, etc.
This goes along with a long-held argument of mine, that those of us (un)lucky enough to make it into popular culture and be eternalized for one thing or other cannot claim ownership over something they did not directly create.
When you become a fixture in culture, you are public domain, like the grand canyon, the great wall of china, the statue of liberty...relatively speaking of course. You don't see anyone paying royalties for using the images of these aforementioned icons.
Hell, this is almost as far-fetched as the Zeppelin family suing Led Zeppelin for defamation of a family name. Seriously, if this were allowed I would have sued Disney long ago for tying my family name (Hercules) to a crappy, third-rate animated film and cartoon.