Google added restricted profiles to Android Jelly Bean 4.3. It's a way to let several people use the same tablet, but each have access to only certain apps or content. You can pick and choose which apps each user can access from settings.
Google is playing it up as a great way to let your kids use your Nexus 7 or Android device, without messing with your email or downloading hundreds of dollars in music. It can also be used for retail kiosks, so customers can only use one app.
The major features announced with Android Jelly Bean 4.3 are restricted profiles, Bluetooth smart capability -- which connects fitness trackers and more to the 4.3 devices --, and support for OpenGL ES.