Penn State has brought “Acquine” online, which stands for the “Aesthetic Quality Inference Engine”.  From an interview in Penn State Live:

Wang said the system extracts and uses visual aspects such as color saturation, color distribution and photo composition to give any uploaded image a rating from zero to 100. The system learns to associate these aspects with the way humans rate photos based on thousands of previously-rated photographs in online photo-sharing Web sites such as photo.net.

ACQUINE: Aesthetic Quality Inference Engine – Intelligent, Unbiased and Instant Assessment of Photos.