Today checking my daily Tweets for development I have found a very good tutorial about face detection using the GD library from PHP.
Karthik Tharavaad have developed a class that will allow you, with very little commands, to detect a face in a photo. As shown on the end of the post, it works well.
More at the post: @Karthik Tharavaad – Face detection with PHP
Post source got from Twitter: @planetphp