On reflection, this may actually be true. The Mona Lisa itself is long out of copyright, but if you take a photograph of it, then you hold copyright over that specific photographic image. That's how art galleries protect their images of the pantings they own. You can't just go to the Louvre's website and use their image of the Mona Lisa.
Yes I can. In fact if you look at the [[Mona Lisa]] page you'll find that this is exactly what Wikipedia has done. Here's is how it's supposed to work:
Museum: Yo! You're using our stuff! Wikipedia: Heh. Yeah. We like your stuff. Museum: FNORD! COPYRIGHT! INTELLECTUAL PROPERTY! Wikipedia: Bridgeman ruling. Museum: D'oh. Wikipedia: Neener.
Regards, Haukur