Amy Argetsinger, who has been out here on temporary assignment in the Washington Post L.A. bureau, was named today as one of the paper's two Reliable Source writers. She tells Washingtonian magazine's Harry Jaffe, "I’m really looking forward to this. It’s going to be quite an adventure." Reliable Source is the Post's reported gossip column. Wonkette's Ana Marie Cox had been a finalist for the job, Jaffe reported last month. Argetsinger will share the duty with Post veteran Roxanne Roberts. (Via Romenesko)