http://www.seomoz.org/blog/beat-google-panda
Interesting article containing the 5 deadly content sins that will hurt you in search engines.
"Panda starts off with human quality raters who look at hundreds of websites. Computers, using machine learning, are then brought in to mimic the human raters. When the algorithm becomes accurate enough at predicting what the humans scored, it’s then unleashed across millions of sites across the Internet.
The point is: Panda starts off from a human point of view, not a machine’s. We can look at these sites with human eyes and see the obvious."