According to GateCrasher:
KANYE WEST had some explaining to do Wednesday night. A source tells us the rapper was supposed to be a surprise performer at the Bronx Charter School for the Arts Auction fund-raiser, which producer Swizz Beatz was hosting at Marquee, but surprised organizers by not showing. The insider says West’s security checked out the Chelsea club before the event to plan how Kanye “was going to get in and out,” and Beatz dropped hints throughout the night. He played West’s tracks, and at one point told the crowd, “I have a really big surprise for you … and he just got a new girlfriend!” — a reference to West’s budding romance with Kim Kardashian. But inexplicably, the insider says “Kanye sent Big Sean in his place.” The Santa Monica-born, Detroit-raised rapper is signed to West’s G.O.O.D. Music label, and though the disappointment in the room was as tremendous as Kim K’s booty, we hear Sean managed to impress a crowd that included Carmelo and LaLa Anthony and Beatz’ wife, Alicia Keys.