Katie Holmes, actress and Bride of Scientology, turns 31 today. Hard-charging hedge fund manager Dan Loeb is turning 48. Brad Pitt turns 46. Steven Spielberg is turning 63. Christina Aguilera is celebrating her 29th birthday today. Dan Klores, the publicist turned documentary filmmaker, is marking his 60th. The head of the American Federation of Teachers, Randi Weingarten, is 52. Memorial Sloan-Kettering president (and Nobel Prize winner) Harold Varmus is turning 70. Troubled rapper DMX is 39. Keith Richards of the Rolling Stones is 66. Ray Liotta is turning 55. Model agency owner Faith Kates is 52. And former Miss USA Tara Conner is turning 24 today. A bunch of weekend birthdays is below.