gfxCardStatus is a free menu bar application that keeps track of which graphics card your MacBook Pro is using at any given time.
Simple, clean "i" and "n" icons that signify IntelÂ® HD Graphics, and NVIDIAÂ® GeForce GT 330M graphics, respectively
Automatically updates when the GPU switches, in real time
Manual update, if you like to make sure yourself
Growl support - so you know right when the GPU switches
Tiny footprint - doesn't sit in your menu bar and hog RAM or CPU cycles
Automatic application updating - checks for, downloads and installs new versions of gfxCardStatus automatically!
Note: only for 2010 MacBook Pros with IntelÂ® Core i5/i7 processors and the NVIDIAÂ® GeForce GT 330M GPU.