Super 8 - JJ Abrams & Spielberg's Secret Project
This is the top secret JJ Abrams project done with Spielberg, which debuted before Iron Man 2.
Looks like Cloverfield set in the desert, or perhaps a Cloverfield prequel.
Something escapes from Area 51 in 1979 and we can thank a mad truck driver who derails a train that contains the creature.
Here is the HD movie trailer for Super 8.