I didn’t even realize that Defense Secretary Robert Gates wasn’t at the inauguration, but there was a good reason why he didn’t attend:

Defense Secretary Robert Gates

Defense Secretary Robert Gates is not invited to Tuesday’s presidential inaugural.

That’s not because President-elect Barack Obama is having second thoughts about asking Gates to continue serving as Pentagon chief. Rather, it is a sign of the great trust that the current and future presidents have in him.

White House spokeswoman Dana Perino said Gates will be sitting out the inaugural at an undisclosed location because the transition teams for the outgoing Bush administration and incoming Obama administration have agreed that Gates is the best choice to lead the U.S. government if disaster strikes the inauguration.

“In order to ensure continuity of government, Defense Secretary Robert Gates has been designated by the outgoing administration, with the concurrence of the incoming administration, to serve as the designated successor during Inauguration Day,” Perino said.

Gates, who has been defense secretary since November 2006, is expected to be at a U.S. military base in the Washington area, inside and comfortable on a day when the temperature is expected to remain below freezing.  [Army Times]