Photo-bans at pop art shows — irony impairment, or Dadaism?

My latest Guardian column, "Warhol is turning in his grave," describes the photography ban in place at the Pop Art Portraits show at the National Portrait Gallery in London. It's an amazing show, and practically every work hung in it violates someone's copyrights, trademarks, or both (this is pop art, after all). In a stunning display of either Dadaism or irony-impairment, the gallery has hung the show with a "no photography" policy (not a "no flash photography" policy, either), and the even extend the ban to the "no photography" signs themselves, which, they claim, are copyrighted works.

Any gallery that bans reproducing Warhol on the grounds that you'll violate his copyright should be forced into an off-site, all-day irony training session.

So what's the message of the show? Is it a celebration of remix culture, revelling in the endless possibilities opened up by appropriating and reusing images without permission?

Or is it the epitaph on the tombstone of the sweet days before the UN set up the World Intellectual Property Organization and the ensuing mania for turning everything that can be sensed and recorded into someone's property?

Does this show – paid for with public money, with some works that are themselves owned by public institutions – seek to inspire us to become 21st century pop artists, armed with cameraphones, websites and mixers, or is it supposed to inform us that our chance has passed and we'd best settle for a life as information serfs who can't even make free use of what our eyes see and our ears hear?