The arm will be crucial for putting samples of soil or powdered rock into analytical instruments inside the rover. A camera and spectrometer to be installed at the end of the arm will also examine rocks and soils in place.
The Mars Science Laboratory will launch from Florida in November or December 2011 and land in August 2012 at one of the most intriguing sites on Mars. The landing site is still to be chosen from four finalists. Once on Mars, Curiosity will study whether the landing region has ever had environmental conditions favorable for life and favorable for preserving evidence of life if it existed.
Learn more about Curiosity at http://mars.jpl.nasa.gov/msl/
This video clip shows engineers in the JPL clean room giving the rover lessons in hand-eye coordination.