From what I've read: It always disables access to contacts, location data, and the like. Apps, however, have their own saved state (say, your score in a game).

From what I've read: It always disables access to contacts, location data, and the like. Apps, however, have their own saved state (say, your score in a game). The idea is they can selectively choose to run in Guest mode when incognito is enabled. It'd be cool if they forced apps to run in a temporary directory like how incognito mode saves cookies in the browser. Apps would appear as if you wiped their data. CyanogenMod's implementation seems like something you'd leave on, though, and constantly losing your data would be no fun (no server to backup all changes you make, unlike the web).