Now isn't this something right out of Minority Report? Last month, Mini placed interactive electronic billboards advertising its upcoming new Mini Cooper models at locations in New York, Chicago, San Francisco and Miami, and they're able to read RFID information off a key fob the company's distributed to Mini owners.
The owners themselves specify whatever information (irreverent or otherwise) they want to be shown on the billboards, and when it's transmitted to the billboards, that phrase is displayed up in lights for all to see.
Seems like a pretty good idea until you realize that you're carrying around a tracking device just to have some fun with a billboard or two. Weird.