Back in 2004, NASA's favorite new toys were the twin Mars rovers, Spirit and Opportunity. They were small little "little-engines-that-could" running around Mars and while the science was pretty good, the P.R. was phenomenal. In the wake of that success, NASA decided that they needed to build another Mars rover. Instead of small and cute, this one, it was decided, would be the bigger, badder rover. Initially named the "Mars Science Laboratory", it was going to be roughly the size of an SUV and carry a wide variety of scientific instruments including almost a dozen cameras, four spectrometers, and the equivalent of a well-equipped weather station. MSL, which has been re-branded as the Curiosity Rover, was the subject of some controversy in it's design phase due to it's large budget of $2.5 billion, it's 30% cost overrun (which by NASA standards isn't all that bad), and it's method of decent.
Previous NASA missions had either used a rocket to get all the way to the ground or used a combination of parachutes and huge air-bags to simply bounce to a stop on the Martian surface. This will be the first time a sky-crane has been used and frankly it's got a lot of people feeling very nervous.
Often we physicist make fun of the engineers in the world. If this works I promise to never again mock an engineer... at least for a week.