Just thought I'd share some info with you for your own analysis. I run an SEO company of about 50 clients. I've been watching raventools like a hawk of course ever since mid April. Maybe some of this info will help.
1: Our SEO site: On April 24th we dropped off the map for all but 2 or 3 huge keywords. As of Monday they had mostly moved back to second or third page, now today quite a few are back but at bottom of first page.
I've done nothing to improve or change this site since April 24th, except i added a blog post on the penguin update (which gets a lot of traffic and leads for us already).
Our back linking strategy revolved around testing lots of WF and link vendors on our site before ever using a strategy for a client. So this site got the **** end of the stick link wise.
2: A client with an international site that has many regional landing pages for local keywords ("keyword" Moncao, etc). His big keywords remained in place but long tail variations and regional keywords dropped beyond page 3 for a majority of his pages on the 24th. They have been slowly crawling back ever since and most are back to page 1 but still well below where they were.
We did nothing to improve this site. Pre penguin we were doing lots of deep linking with a wid mix of anchor text. His anchor text heavily favors brand, and "visit us" type keywords. He should not have been penalized for any anchor text over use. I think something else went wrong here.
3: Another ecommerce client was untouched as of April 24th, in fact their traffic was up by 17% by may 4th. But as of this week they have dropped on long tail keywords too, by as much as 2-3 pages for almost every keyword, some off the map.
So this Penguin update must be rolling out still. This site has a huge social presence, very high quality inbound and natural looking links, but there are some mixed in low quality signals with that.
Anyway, none of this has helped me put together any solid theories other then the update isn't done and changing things on your site is probably not something to do just yet as rankings came back on several sites without touching them.
Maybe it will help some others figure things out though.