Though Talladega Nights: The Ballad of Ricky Bobbyrepeated at the top of the box office (its total of $23 million was down 50% from last week), the big surprise this weekend was the success of Step Up. The poorly reviewed teen dancing flick earned $21.1 million on fewer than 2500 screens via a per-screen average of $8500, easily the best among mainstream films this week -- who knew that a supporting turn in She's the Man had turned Channing Tatum from former model into box office god? Since the film cost only about $12 million to make, one assumes the people at Buena Vista are doing a little celebrating today.

Also doing solid business during its opening weekend was Oliver Stone's World Trade Center, which made $19 million from Friday to Sunday, earnings that ran its total to $27 million over five days and were good enough for the third spot in the weekend charts. Rounding out the top five were Barnyard which, unaffected by awful reviews, made $10.1 million in its second week in release, and J-horror remake Pulse, which earned only $8.5 million despite an exposure roughly equal to that of Step Up.

Full numbers are after the jump.