Lion: One-finger-swipe on Magic Mouse in Finder

For now, you could setup a gesture in better touch tool, which is free.

MagicPrefs is a nice app and the price is right. Unfortunately it doesn't have one finger swipe settings. 😟

Under System Preferences > Mouse > More Gestures > Swipe between pages

Set to "Swipe with one or two fingers"

You can now swipe back and forth in Finder wih two fingers while retaining other functionality.

O.K. It does uncheck Swipe between full-screen apps. I guess its one of the other. My mistake.