The 2008 and 2009 Super Bowls were scheduled to kick off at around 6:20 PM. The 2009 Super Bowl will probably actual kick off about the same time the 2008 Super Bowl did, 6:32.
3.32pm - PST (includes California, Seattle)
4.32pm - MST (includes Phoenix)
5.32pm - CST (includes Chicago)
6.32pm - EST (includes New York, Boston, Ohio)
More about last year's official times:
FoxSports, which broadcast the game, plastered "Kickoff 6:17 ET!" all over their site.
Many sources indicated that the game will start one minute later, at 6:18 PM. These sites include the official NFL site (www.superbowl.com , and www.nfl.com/superbowl, which it redirects to), the University of Phoenix (where the game was played) site, and Wikipedia.
The official Arizona SuperBowl site http://www.azsuperbowl.com/game_day.aspx was the closest, predicting that kickoff would be at 6:30pm EST.