Android 4.1 Jelly Bean has unofficial multiple user support. Having multiple user accounts on a shared tablet is very useful in enterprise. Many people would use different account to read email or download apps on sharing nexus 7.
How to Enable Multiple Users profiles on nexus 7 or Jelly Bean device
* Install Android Terminal Emulator by ack Palevich from Google PLay and root the tablet. Open the app and enter the following command line in
pm create-user testuser2
This creat the 2nd user named "testuser2". To remove it, use "pm remove-user 1" command.
* Hold the Power/Lock buttons and tap on the new Label in the menu to switch to the new user. This gives you a fresh home screens, in-app accounts and settings.
* You can also edit the "userX.xml" file in /data/system/users, or use the "User Management" by Appaholics in GUI to get the limited multi user (It works but causes other apps run lagged badly).