Beetlebug Software - Blog
http://blog.beetlebugsoftware.com/post/104154581/face-detection-iphone-source

Picture Me was a fun little side project to experiment using face detection on the iPhone.  I have a few ideas on where to take this but I don’t have time to work them now.  So for now, it’s free.  And as an added bonus I’m releasing the source code for it in the hope that it will be useful to the iPhone developer community.

For the "when I get asked to do that in a month" file.

Source for an iphone face detection app.

Serviço de face detection com API bem bacana. Vc faz um pedido via API com o endereço da imagem e ele te retorna um JSON com as faces detectadas.

face.comが顔認識のAPIを公開。