Re the mulitiple listings I'm seeing them too. For one of our main three word keywords which form a question. There's us, then a quiz asking the question, 2 facebook pages, a youtube vid, then exactly same quiz, albeit appearing on a different site. Has the same title though !
Same for another keyword phrase. Theres a load of country specific Yahoo answers, followed by another load from the .com. One after the other at no2 and no3 spots.
Certainly there doesn't seem to be much in the way of diversity in the results I'm following, and very little in the way of smalled informational based sites as opposed to throwaway fun quizzes and barely relevant 'answers' and discussion results from much larger sites.
Our traffic took a bit of a nose dive also on the 20th. Yet our serps seem ok strangely.