From http://www.custompc.co.uk/news/604788/ghostbusters-is-first-film-to-be-released-on-usb-stick.html,

Are you the USB keymaster? You could be soon if you pick up PNY’s new 2GB USB flashdrive, which comes with Ghostbusters pre-loaded. While the music industry has been playing around with USB flash drives for a few years now, the movie business is still relying on discs, but that may change following this partnership between PNY and Sony Pictures Home Entertainment.

You can pick them up from Argos apparently for £30. That seems like an awful lot of money to shell out for a movie you can buy on DVD and rip to your PC yourself for about £1.