The Samsung Galaxy S is one of the best Android phones in the market right now. The phone has a 1Ghz Cortex A8 based Hummingbird processor, and 512MB of RAM. The Galaxy S features the best combination of CPU + GPU on an Android device. The Galaxy S is sold in the U.S under different operators and under various names like Captivate and Fascinate. With the various lag fixes available for it, the Galaxy S beats all other devices in Quadrant benchmark irrespective of their Android OS.
However, for some developers this was not enough and they have gone ahead and overclocked their Galaxy S to 1.2 GHz. The Hummingbird CPU inside the Galaxy S can be overclocked to 1.6 GHz safely. Interested readers need to flash a modified kernel to overclock their CPU to 1.2 GHz. They also need to download SetCPU from the Android Market. Here is the link on how to overclock Samasung Captivate to 1.2Ghz .
Keep in mind that the above link is valid only for Samsung Captivate owners. Samsung Galaxy S owners need to check this thread on how to overclock their CPU.