optical zoom with CHDK works on most cameras. I have a SX110 and S90 and they both now can zoom while filming. But you will get the zooming sound recorded in the audio (the zoom motors are just too noisy). But I have also An A590 and that one can NOT zoom in movie mode even with CHDK, but this should be with the minority of cams.
(Sorry to bump such and old thread, but that question was not answered and someone else might be looking for this).
