The scrolling up and down is a very useful feature of the Apple Magic Mouse. You would not want to turn this off. But it is a bit of a nuisance on Google Maps because it is so easy to indadvertedly make the slightest up or down wipe that unwantedly zooms the map in or out. Even if one is wanting to zoom by this mouse, it goes too quickly, not well controllable. I use the bar + - control they have on the top left as much as possible instead. No good turning javascript off (in browser) because then the map does not work at all right. Google should adjust their javascript.