I think this update is primarily going after EM Anchor Text/Full Site Links. I've looked through a few sites that took a hit, pretty big Link Graph issues, but they all had a fairly large number of exact match anchor text links from very few sources (5-7). Rather then build up the number of referring domains, I am just removing them from the link graph to see what happens.
Note: It is not content, Google ranked these sites pretty high for a multitude of terms and the sites had steered clear of any and all panda updates.
Anyone notice anything similar?