The NY Post has learned that orphan-collecting Angelina Jolie Manbot Brad Pitt has joined the cast of “Nip/Tuck” mastermind Ryan Murphy’s upcoming reality-based political drama DIRTY TRICKS. Based on the John Jeter play of the same name, the film stars Meryl Streep as Martha Mitchell, the wife of Richard Nixon’s attorney general John Mitchell, whose knowledge of the Watergate break-in played a key role in bringing down Nixon’s presidency. Pitt will co-star as White House Counsel John Dean whose wife, Maureen Dean (played by former Pitt flame Gwyneth Paltrow), refused to admit her husband’s involvement in the scandal. Sharon Stone, Annette Bening, Jim Broadbent and Jill Clayburgh also co-star. Production is expected to begin in December for a 2008 release. Pitt can next be seen in the deliciously long-titled western THE ASSASSINATION OF JESSE JAMES BY THE COWARD ROBERT FORD, the David Fincher drama THE CURIOUS CASE OF BENJAMIN BUTTON and the Coen Bros.’ dramedy BURN AFTER READING. He can also be seen scouring third world countries for orphans to enhance his ever-expanding multi-ethnic brood.