Today, Facebook is proposing a series of changes to its terms if service. There's a lot of legal mumbo jumbo, but the most interesting piece is that Facebook is going to use your profile photo as the basis for suggesting that you be tagged in your friends' photos.
So far, Facebook has only posted a section-by-section summary of the changes has been posted, but the actual tracked changes document isn't online yet that we can see. Luckily, ATD has the relevant section in its news post:
We are able to suggest that your friend tag you in a picture by scanning and comparing your friend’s pictures to information we’ve put together from your profile pictures and the other photos in which you’ve been tagged.
The old language:
We are able to suggest that your friend tag you in a picture by scanning and comparing your friend's pictures to information we've put together from the other photos you've been tagged in. This allows us to make these suggestions.
In other words, your profile pictures will now figure into how Facebook figures out what you look like. In the short-term, it will improve the company's facial recognition so that it can suggest you be tagged in more photos. And of course, if it can find you all over the site, then it's got a more comprehensive sense of who you are.