Measure the frames per second on a mac
It depends on what you're measuring.  The screen refreshes from video memory, and the video memory is modified by the OS or by OpenGL commands executing on the GPU.

If you run two quicktime movies side by side, the will separately update the video memory, and could have two different frame rates based on the system load and several other factors.

Any tools to measure framerate would need to measure just one applications framerate.  Many applications, such as video players and video games, can report their own framerate.  

Further, any software tool will consume system resources that may affect framerate.

When I've had to objectively measure framerate for an app that didn't measure and report framerate itself I've used a high speed camera (for consumers the PS3 camera is considered high speed) and then examined the frames of video for display updates to determine the framerate.

The Macbook Pro display refreshes 60 frames per second, and no faster framerate can be displayed on it. These techniques would only measure framerates below 60.