A barebones and half-working version of Android 4.2, packed with placeholder graphics to make it look even rougher, has been leaked, with one of the key discoveries so far being the inclusion of support for multiple user profiles.
According to Android Police, the code features additional Android app permission requests which would cover apps being used by one or several users, so you may be prompted to specify if you'd like apps to be used by everyone or just the specific downloader when installing Android apps in future.
An entire sub-section simply called "Users" has also been found in the preliminary Android 4.2 code, allowing phone owners to add and delete new users, set photos for specific accounts and edit their profiles. So even if multiple user support doesn't arrive as part of Android 4.2, it's definitely something that's being worked on for future Google hardware. [Android Police]