Pictures of Britney Spears, Beyonce Knowles, Jay-Z, Justin Bieber, Selena Gomez at the 2011 Billboard Awards

Last night's Billboard Awards, held at Las Vegas's MGM Grand Arena, were star-studded from start to finish. A pantless Britney Spears and Rihanna kicked off the proceedings with a scantily clad rendition of "S&M," and Brit later took the stage again for a performance with her tourmate Nicki Minaj. Beyoncé Knowles was another of the evening's biggest draws, and she was on hand to sing her new tune "Run the World (Girls)." There was an honor in store for Beyoncé as well, since she took home the Millennium Award and made a heartfelt acceptance speech that included a shout-out to her husband, Jay-Z. The night seemed to belong to Taylor Swift, though, with her win for Artist of the Year. Justin Bieber and Selena Gomez's live kiss gave Taylor some competition for the spotlight, however. The festivities were presided over by The Hangover Part II's Ken Jeong, who had some help from his costars Bradley Cooper and Zach Galifianakis in introducing urban music — that is, tunes from Keith Urban.