Still waiting for an update to ICS on your device, or it just wont support latest face unlock. Now you can download FaceLock available in Google Play Store. Its different than the basic face lock feature which comes by default in Ice Cream Sandwich. Users can enable this app and increase the security level by another added layer. It not only gives you the option to set face lock as your primary phone security but it can also be applied to apps. Hence, adding more security to device settings, and installed applications.
Developer strongly believe that the task manager, device settings and Google Play store is protected, so FaceLock cannot be removed or stopped.
Paid version comes with unlimited app locks, lock screen replacement, pattern lock, set alternative access method, delayed lock, hide notifications and more. Both free and paid versions, run no advertisements. This app was successfully tested on Nexus S and Galaxy Note. It would support any device running 2.3 and higher.