I recently received an email about a product called Justick. Its basically a bulletin board without pins, tapes, etc - where notes just stick, without any additional aid. This works via an electromagnetic field, generated by AA batteries.
While this probably is not robust enough to hold up in some environments, I could see uses. If you could control the power remotely, things could easily fall onstage. But I could see it more in use backstage, or for use in meetings where you may not have a post it note, but need to make a note.