Since 2 days there's clear movement for sites previously hit by Penguin 1 and Penguin 2.
What's Going On
A significant number of sites came back from nowhere to rank on page 2-4 for their head keywords. These head terms are all very competitive keywords. The affected sites had excessive keyword anchor text pointing at them.
With these keywords now back in play we're seeing a 10-20% improvement in Google referral traffic.
This is clearly a happy update, an improvement update. No site in SEP's extensive portfolio is negatively affected by this update. We only see improvements . No site is going further down.
What Was Done
Remarkably, among the sites positively impacted, some went through a disavow process while others haven't been touched at all.
One can speculate that as wave after wave of disavows ripple through Google's trust index, some pages and perhaps even entire websites are taken out of the link graph. The cumulative effect would be that links to sites who aren't disavowing are none the less disappearing with a net effect of the site recovering.
Likewise, the destruction of mass-based link selling sees sites closing shop. Again, the net effect is that less (bad) links are in place to the sites.
What Wasn't Done
No link building has been performed for any of the sites that have improved. Expecting their traffic to reach the levels of pre-Penguin days is therefor unrealistic.
It's also possible that a certain distrust status remains applied to these domains. This, too, can prevent the sites from regaining their old traffic levels.
What You Should Do
If your site was hit by one of the Penguin roll-outs, log into your analytics to see if traffic has improved over the past couple of days.
For those sites that see improved Google referral traffic, check your Google Webmaster Tools to evaluate the Penguin severity. This will help you determine if the site will benefit from new content.
If you see the site ranking 1st page for meaningful keywords, brand related keywords excluded, and there is some search volume attached then this is a good signal that Google is fine with the site now and any new content has a good chance to rank.