It was being used for Password by Lenovo laptops. Now Google and some other lesser known companies are making a foray into Face Recognition, Classification and Indexing software. This software may ultimately be used for classifying and finding similar images on the net.
It could be used to locate Images infringing copyrights. It could be used to search products on the net based on Image. An image search. OR searching for some complicated part or assembly.
Ultimately it looks like moving towards Web 3.0 applications or semantic web where all the images could be intelligently classified and used.