Canon has started using the newer DIGIC6 processor , although mostly on its higher performance models like the S120. Cameras using the DIGIC6 are not compatible with the current CHDK build and tools so it may be a long time before someone takes the time to create the first port.
If you decide to buy an S120, there is no guarantee that CHDK will actually get ported to it.
link> CHDK FAQ : My camera isn't ported yet
