The most exciting news from Labor Day weekend at the box-office -- traditionally a slow period -- is that America seems to have caught on to the scam that Jason Friedberg and Aaron Seltzer have been running for... what is it now? Almost three years? (I'm not counting the Scary Movie franchise, which always retained some redeeming value despite their idiocy.) Anyway, their latest travesty, Disaster Movie, opened to $6.9 million over four days, just over a third of the (nearly identical to each other) first three-day weekends for Date Movie, Epic Movie and Meet the Spartans. Could that be the end of that?

Not that any of Disaster Movie's competitors did spectacularly better. The strongest of them -- the poorly-reviewed sci-fi flick Babylon A.D. -- only managed second place and a $12 million four-day. Don Cheadle's Traitor came in fifth with $10 million, which I actually think is robust for an barely-marketed film opening on just over 2,000 screens. College crashed and burned, landing outside the top 10 with $2.6 million. The best explanation is that there simply wasn't any reason to see it.

The holdovers did well. Mamma Mia!, now in its seventh weekend of release, continues to lurk in the bottom half of the top 10; its take actually grew compared to last weekend, even if you use the 3-day numbers. It's up to $133 million. The Dark Knight barely lost steam, going from fourth place to third and breaking the $500 million threshold. Vicky Cristina Barcelona also continues to do very well on under 700 screens. And of course, Tropic Thunder managed a third weekend atop the charts, leapfrogging past Pineapple Express.

The full estimates after the jump.