MEDIA bigs turned out in droves for the birthday party of Shirine DiSanto, wife of MTV programming president Tony Di-Santo, at Meatpacking District hot spot SL the other night. Helping the couple celebrate were Russell Simmons, “Today” show executive producer Jim Bell, Niche Media’s Jason Binn, former Sony honcho Charlie Walk, Brian Baumgartner of “The Office,” Seth Meyers of “SNL” and Eric Mabius of “Ugly Betty.” DiSanto joked that while he was surprised to have married the woman with whom he started at MTV as an intern 20 years ago, he was more shocked that he was “still [bleeping] working here!”