The next operating system should recognize faces from camera & apply the settings accordingly independent of whether he is logged in or not1. The user need not be the actual user created in the the system, and even if he/she is the user of the computer, these setting should be different from the actual user settings. The operating system should not give the rights of the user of whose setting is applied but only make changes in the user setting 2 .The changes can include wallpaper, play list, theme, recent documents etc. The system should understand and learn from user preferences and not just apply the last setting.
The system can also understand the mood the user and the guest prefers when they both are in the room and apply the settings accordingly.
Note:- if such setting data for a guest doesn’t exists than computer should start learning from new user behavior and once the user is gone it must ask the administrator and the guest weather the user data has to be saved or not3 . This is to save hard disk space.
1 System ,if required, can wait for some time (of continues presence of guest) before applying the settings.
2 The system should somehow recognize when the setting has to be applied.
3There can be many variations to this: The computer doesn’t ask and automatically deletes the setting after fixed number of days or the administrator can give right to users to delete the new user for whom data has been created at the time when these user were logged in.