It was a memorable New Year’s Eve for the Cosmopolitan Hotel party goers.  The posh hotel opened its doors at the strike of midnight with a performance from Jay-Z, ColdPlay’s Chris Martin, and “surprise” guests Beyonce, John Mayer and Kanye West.  Their celeb friends like Taraji Henson, the Whitakers, Christina Milian, Brandy and more came out to party too.