MSL

Mars Science Laboratory is the next big NASA flagship mission to Mars, and in light of Phoenix and the energizer-bunny MER craft, MSL does not receive much press. This is probably for the best since it doesn't actually do anything yet, but I thought it would be worth presenting here.
MSL will launch on an Atlas V (largest American rocket) sometime in mid-late 2009 and will land in mid 2010. It is significantly larger than the MER and Phoenix, and it is expected to live for at least a full Martian year and travel up to 12 miles. The size of MSL is a huge factor in the mission plans for obvious reasons: it will be able to travel over large boulders and small obstacles will not be an issue as they have been in the past, but it has to be launched in an Atlas V which will drive up the cost significantly, and it can't land in the bouncy-ball method used for MER. Current plans for landing are similar to that of Phoenix, except a rocket-propelled crane with lower MSL to the ground before flying off to crash elsewhere on the surface.
The actual science MSL plans to do is what you might expect: study the geological properties, study the atmosphere, search for evidence that life existed or find if microbial life does exist, and prepare for an eventual manned mission.
Some news on MSL can be found on the JPL website at http://mars.jpl.nasa.gov/msl/mission/tl_launch.html
There are some nice pictures of when the press was there and JPL did a driving demonstration. You can tell that this rover is meant for some more serious driving than the MER craft. Construction and testing of the rover itself will begin early 2008; it will be interesting to see how the success (or failure) of Phoenix affects the MSL development.