One disappointment of Oscar week is the omission of Nicolas Berggruen’s annual party at the Chateau Marmont, reports The Post’s LA correspondent Richard Johnson. Known as “the homeless billionaire” for living in hotels and his jet, Berggruen, 51, customarily attracted a crowd of tycoons from both coasts as well as a large number of gorgeous young women. But disappointed guests from years past speculated that bachelor Berggruen’s now aiming for a career in politics and doesn’t want to tarnish the serious work of his Berggruen Institute in Santa Monica, which aims to foster good governance globally. Besides a $20 million effort to fix California’s budget, he’s launching commodities exchanges in Africa and building Richard Meier-designed housing in Newark. Berggruen’s 21st Century Council includes Tony Blair, Gerhard Schröder and Joseph Stiglitz — a group not known for hard partying. We hear instead of the boozy bash, Arianna Huffington will throw Berggruen and editor Nathan Gardels a reception at her home tonight.