This is all the roadways' demonstrative arseholes need — a way to fire off literal rejoinders to fellow motorists' hand gestures. It's a new LED scroller that can convey advertising (or other) messages. The company that makes it, MobileLED, appears to be downplaying the product's use by consumers looking to "make conversation" on the road — copy on its website reads, "you can program up to 60 customized advertisements." Advertise this, you $%@&#;! moron.
Related:
Car-to-Car Gaming: Electronic Road Rage [internal]