@turbocharged - thank you for your comments. Would you please elaborate on "cached google appspot proxies". I have never heard of this before.
serpsguy, go to google and search for the following without quotes: google appspot proxy hijack
Google owns appspot and many people create proxies on them. Because appspot is owned by Google, it has high domain authority. Proxies running on this domain can essentially copy an entire site, renaming the urls to that of the proxy it resides on. Instead of a single page being duplicated, it can create major duplicate content problems if your entire site appears under a cache on some appspot subdomains. Our client had been copied on well over 100 appspot subdomains.
Unfortunately penguin 2.0 did nothing to reward original authors or at least offer a safeguard. I'm seeing the same duplication as before. I believe that the problem is many of these scrapers simply scrape, post and build no links to their stolen content. Original authors, on the other hand, are more likely to promote their own content and are at risk of being demoted by penguin for unnatural links. It is also possible that some other pages that are hit by penguin 2.0 pass this penalty to new pages, which also leaves them at risk of being scraped by a "cleaner domain" and ranked by someone other than the original author. This may be why so much copied content is rising to the top of the serps while original authors are sinking.