Fujifilm's F300EXR compact camera features fast hybrid AF combining contrast AF and phase detection AF into one. To support phase detection AF the camera Super CCD EXR sensor is enhanced with built-in phase detection pixels:
Pixels used in the phase detection AF are marked by 1. Fujifilm does not say how many pixels are entirely devoted to AF. It is not clear why they appear smaller too.
Update: DPReview has a detailed explanation of how Fujifilm phase detection AF works.