Since the MayDay update there have been a spike in complaints about site's with stolen content outranking the sites they stole the content from.
This is an old issue, which Google was typically not too bad at handling. You have 5 web sites, one web site wrote the content first, then the other four snatched the content from the original source. Google was typically good at knowing who was the original source and ranking that original source higher, independent of which site had more PageRank and authority.
Since MayDay, it appears that original source detection has gone a bit haywire.
There is a large WebmasterWorldthread and a new DigitalPoint Forums thread with constant complaints about Google ranking scraper sites above the original source.
Is it Caffeine or MayDay related? Is it that Caffeine is discovering content faster on the scraper site, thus giving them the original source credit (if it works that way)? Or is it a ranking algorithm change with MayDay, finding original source credit less valuable then other criteria?
Tedster's theory:
It comes from Mayday giving good rankings to "sites" they feel are more popular - and therefore better over all destinations for the search user. The emphasis used to be more on the "page" rather than the "site".
Have you found this to be a larger issue since MayDay/Caffeine?
Forum discussion at WebmasterWorldthread and a new DigitalPoint Forums.