NASA has begun a contest for American students (K-12) to name the Mars Science Laboratory Rover.
The MSL is currently being built and tested. It is scheduled for launch in the Fall of 2009 and land on Mars in the Summer of 2010. MSL is a nuclear-powered rover that is the size of a car - roughly 15 feet long by 9 feet wide by 7 feet tall. MSL will travel about 20 kilometers, drill holes in rocks and analyse the dust in a chemical laboratory. Rocks will also be zapped by a laser for analysys.
Hopefully, the Martian AeroSpace Defense Command won't consider the laser-zapping a hostle act.
Link to Mars Science Laboratory mission web site.