Dan Bartlett, George W. Bush’s advisor for the past 14 years, through four campaigns,  six years as Governor of Texas and six as President, has resigned on his 36th birthday:

WASHINGTON (AP) — Dan Bartlett, one of President Bush’s most trusted advisers and his longest-serving aide, said Friday he is resigning to begin a career outside of government.
CNN.com – CNN Political Ticker

Similarly, Tim Griffin, former aide to Karl Rove, and recently appointed US Attorney, will resign today:

The former White House aide whose appointment to a U.S. attorney’s post helped fuel the furor over the forced resignations of eight federal prosecutors will resign Friday, according to a news release. Tim Griffin, 38, said in a Thursday statement that he is leaving his position as interim U.S. attorney for the Eastern District of Arkansas to pursue opportunities in the private sector.
Ex-aide to Rove resigns amid U.S. attorney flap – CNN.com

Now, when will A.G. Alberto Gonzales go?