Noticed there was a link from A570IS CHDK Wiki to a review I had never read.
http://www.trustedreviews.com/Canon-PowerShot-A570-IS_Digital-Camera_review
Saw "My only real complaint was that I found that the zoom control to be rather unresponsive. The zoom is stepped rather than continuous, with only seven positions between telephoto and wide angle, so accurate in-camera framing proved to be impossible."
Has this complaint zoom unresponsive and stepped aspects been solved with CHDK? For Stills? For Videos?
Probably not - CHDK just calls existing camera functions to operate the zoom features. If the camera runs the zoom in "stepped" mode then CHDK will run the zoom in "stepped" mode.
However, I have to ask, if you hadn't found the article you quoted, would you even have noticed ?