It's only my opinion of course, but I think this update includes two important changes, one being a panda and one being a penguin.
The EMD stuff I think is an update to panda, which passes judgement on the quality of content for the page to determine how well it ranks. We know that 'low-quality' EMDs were hit. How does Google judge quality? From the training manuals given to Google employees for manual review, we know that when evaluating quality these factors are examined:
- The page must have a clear purpose. 'Spun' content gets labelled by Google as serving no purpose, and we know that Google is working hard to improve the search engine's ability to detect good quality grammar, so the quality of the written content (grammar-wise) is supposed to be good.
- Main content, supplementary content, and ads should all be distinguished one from another.
- The main content will be assigned a quality rating. Social sites are given high quality ratings, author's "authority" is also considered (in a manual review, but the inclusion of recognized Google authorship should tend to favor you). Streaming videos are specifically mentioned, as are Wikipedia pages and 'high quality blog posts'.
- The main content is also considered on its QUANTITY - so short blog posts are supposed to be tougher to rank now.
- The supplementary content is considered on how 'helpful' it is, which would likely be keyword relevant links to other blog posts type stuff.
- The navigation and ease of finding the home page as well as its 'design' is specifically mentioned.
- The site and its owner's 'reputation' is considered.
We talk about how Google wants bad results to show in organic listings so people click the ads that pay Google. Nobody doubts that this is what Google wants, but we also have to consider that Google wants to reduce the work load for its spam review team by making the automated results conform to the elements in the manual review - so these elements should all favor your website if done the way 'google wants them done' and the EMD gets a bad rap if the quality of the content on it gets a bad rap.
Now I also believe that Google has updated the Penguin, which checks the off-site quality factors. We can only guess at exactly what has changed, but I've been experimenting over the last 10 days or so, and I have seen positive results from two primary link-building sources: major social networks (Twitter) and link-pyramids (crap links to the social sites like Tumblr which link to my main site). These two sources both conform to what Google considers quality on the page that the links are on. They've specifically mentioned that social websites are favored, so I'm now turning my focus in link-building this week to hit these two sources hard.
Once again, this is all opinion and comes from my observations of what I've been experimenting with.
