Robert Downey Jr., 35, was arrested for drug possession in the Southern California desert playground of Palm Springs on Saturday night, say police. An anonymous 911 tip at 9 p.m. led authorities to apprehend the actor — who was by himself with cocaine and methamphetamine — in his room at the Merv Griffin Resort Hotel, Palm Springs police officer Ralph Landry said in a statement. “He was conscious and conversed with the officers,” said Landry, who described the actor as “very cooperative.” Downey was reportedly released at around 6:30 a.m. local time yesterday on $15,000 bail and is scheduled to be arraigned on Dec. 27. All this occurs as the newly buffed Oscar nominee (for 1992’s “Chaplin”), who was also being talked up for a supporting actor nod next year for the current “Wonder Boys,” was said to be getting his life and career back on track. In August, he had been released from prison after serving one year for drug-related charges. (Downey’s brushes with the law hark back to 1996, when Los Angeles police stopped him for speeding and then found cocaine, heroin and a gun in his car.) Besides his recurring role on TV’s “Ally McBeal,” which he nabbed immediately after his prison term, Downey is slated to star in a Los Angeles stage engagement of Shakespeare’s “Hamlet,” to be directed by Mel Gibson, planned for early next year.