With a cost of around 2.5 million dollars for 30 seconds during the Super Bowl, I can guarantee that GM will not spend it on the Z28. They have a lot more time and money spent on global cars and any ads will go towards re-cooping those costs first. GM knows that they will get a ton of free advertising by just posting a picture on the internet, they will not have to worry about promoting the Z28, it will sell itself. Official debuts will most likely not occur before next summer when T3 breaks into the movie market.
Walk softly, carry a light saber and drive a ZL1!