The ChemCam system is a more or less standard-ish laser induced breakdown spectroscopy (LIBS) system. One of the key advantages of using LIBS on Curiosity is that it can analyze somewhat distant samples, which is fantastic for a rover that has a top speed of 0.09 kph. There are several example videos on youtube, here's one: http://www.youtube.com/watch?v=1AtI3t1T5zk