Aside from the advertising angle, there's not many of those 'benefits' listed there which couldn't be achieved more cost effectively than with a traditional sticker (i.e. the handicap badge, etc). Police cars tend to already identify stolen or unregistered vehicles, and I don't see why adding vanity messages would be worth the additional money.
All I can see here is increased complexity and cost, with a much shorter lifespan than a traditional aluminium or plastic plate.<p>Of course, setting it up to have a refresh rate that was out-of-sync with multinova speed cameras (and distorting any captured image of it) would be interesting.