High-def billboards coming to a highway near you

You know the billboard that flips every few seconds to show a different advertisement? There's a new player in town that will be right up your alley: HDTV billboards.
These billboards are the same style that are used in stadiums. They are not cheap ether as they ring in at close to $500,000 a pop but they sure will be nice looking, i.e., Times Square. Don't expcect to see fast moving images on them as that's something that just doesn't sound safe.

Has anyone seen these things yet? Apparently they are already up across the country but we haven't seen one yet.