For the life of me I can't get the zoom feature to work on OSX 10.6 on my Max Mini. It's a fresh install, I have the wireless mighty mouse with the small grey scroll ball and the small wireless Apple metal keyboard.
I've tried enabling "Zoom using scroll ball whilst holding ^Control" mouse System Preference.
I also tried enabling Zoom in "Universal Access" in the System Preferences.
This did work in OSX 10.5, but seems to have stopped since I installed 10.6.