In my quest to make it easy to extract the maximal amount of information from my photos, I wrapped libfacedetection:
It works pretty well, but still needs to down sample photos (it will not recognize faces correctly on e.g. a 3000x3000 photo)
Next mission: recognize faces! If anyone has pointers on the state of the art, let me know!
Last thing I learned was still mostly PCA + Eigenfaces