Everyone’s favorite College Dropout had a birthday last week, and the celebs were out in full force to celebrate. Jay-Z, Diddy and Mariah all came out to pay Kanye their respects on his 30th at the Louis Vuitton flagship in New York, even if the caterers didn’t feel compelled to — apparently the Great One’s name was spelled incorrectly on the cake, as "Kayne." Also in attendance were Ashlee Simpson and Fall Out Boy’s Pete Wentz, who had earlier joked to VH1.com he was getting Kanye a knock-off Louis Vuitton bag for his birthday. Noticeably absent? Ye’s hip-hop hall pass buddy John Mayer. Their harpsichord-laced track "Bittersweet" leaked last week. A pre-Jessica John fills in the funny on the making of the first single off Kanye’s latest.