Ralph_Slate - 5:22 pm on Oct 24, 2012 (gmt 0)
Here is what I observed:
April 24: 60% reduction in Google search traffic. I saw many instances of a "-10" penalty, with my site at position #11 in the SERPs. Other pages were gone completely.
I never bought, sold, or traded links, and my site has a *ton* of backlinks since it has been at its URL since 1999 and is a leader in its niche.
I changed a bunch of things on the site over the summer, 80% of which were so-called "quality" issues (i.e. Panda). Made navigation better, removed some thin content, reworked my titles and H1 tags. As for link-related changes, I made about a dozen outbound links "nofollow", removed some spam from a VBulletin installation (not much), and blocked a development server (on a separate domain) from being indexed by Google.
Oct 11. my traffic came back, and the "-10" pages are now at #1, and the other pages are on page 1 or page 2 of the SERPs.
Please treat this as just another data point, I'm not saying that this is the cure.