I dumped years of photos into Picasa and it began scanning the pictures to find faces. This capability is not new, but I was surprised at how well the application works. It accurately identified people in my photo albums even if the photos were years, or even decades apart.

As an example, here are two photos of my Grandfather that Picasa correctly identified. The first photo is from 1943 and the second photo was taken in the early 90's. 

I recommend giving Picasa a try. I prefer it over Flickr and other similar photo applications.