If you find PIN codes or gesture patterns too predictable to keep your phone secure, Ice Cream Sandwich has the ultimate solution: face unlock.
Face unlock utilizes your phone's front-facing camera to "recognize" your face. If anyone else looks into the camera, they will be denied access. Simple as that. Not only is this a nice option to have for everyday use, but I could imagine it being integrated into mobile security apps as well, ensuring that no one but you could get into your phone and see potentially sensitive data.
In tonight's demo, face unlock experienced quite a hiccup - it didn't recognize the face of the presenter, who was also the phone's owner. Google still has a little time to get this right, however, but it certainly seemed a bit embarrassing, getting duped by a feature that may not quite be ready yet.
At any rate, this feature promises to seriously step up your phone's everyday security, and seems like it will a fun feature to try out once we get our hands on Ice Cream Sandwich.
Update: video demo by Engadget: