Snapdragons, the OMAP on the Droid, and the Samsung on the iPhone are all System On a Chips. Each one has a graphics processor and a main processor. No one knows the exact spec of the iPhone graphics processor but all signs point to the same PowerVR in the Droid, but possibly faster. All three processors in each SOC are all Cortex A8 based, so their Mhz should be comparable (Snapdragon possibly being the fastest, then the OMAP and Samsung somewhat tied). This means that the Snapdragon SOCs are probably the fastest overall in terms of system performance and graphics performance. Then the Samsung, then the Droid's TI OMAPs.