As you may know the new MacBook Pro uses two different graphics cards. The built-in Intel HD Graphis 3000 and the AMD Radeon HD 6750M for example. Depending on the graphics power needed, the MacBook Pro dynamically switches between the two. To find out which GPU is in use check out gfxCardStatus. The open-source tool even lets you switch between the cards manually. Useful in case you want to safe battery juice while on the go. gfxCardStatus also tells you which programs are demanding the faster chip (and sometimes unnecessarily).