Watch out, D.C. — our local slice of the internet is experiencing some serious mood swings today! This morning, it was all doom and gloom after the announcement of Gabe Klein’s departure, among several other well-thought of agency heads, like DCRA’s Linda Argo and OCTO’s Bryan Sivak. (Sivak himself sounded really broken up about having to step down.) But things have apparently brightened up a little bit this afternoon, as Vince Gray has announced that Allen Lew will be city’s next City Administrator.

Dan Tangherlini On the heels of Nikita Stewart’s scoop last night that people have been getting vetting calls from the FBI about D.C. City Administrator Dan Tangherlini, D.C. Mayor Adrian Fenty called a 3 p.m. press conference today to announce a “Cabinet-level” personnel announcement. And the word has just come down: Tangherlini is off to Treasury, where he’ll serve as assistant secretary for management, chief financial officer, and chief performance officer. That’s sure a…