An interesting story in Business Week explains how and why the price of Super Bowl commercials has risen so much since the first game in 1967. One of the reasons that the game commands ever-increasing prices from advertisers is that viewers don't change the channel when a commercial break comes on. The audience levels for advertisements are higher than for the on-field action.
And how much is a 30-second advertisement at this year's Super Bowl expected to cost? A cool $4 million.
(Thanks to Max Massey for pointing out the Business Week story.)