smithaa02 - 2:29 pm on May 14, 2012 (gmt 0)
It appears there is a strong correlation...
For each of your sites hit by Penguin, respond to the thread answering if you did link-build for that site or not. Might be telling. Obviously don't show your website.
I'll start. Only one site of ours got hit and we did link-build for it.