In January 2011 Google launched Panda Algorithm update meant to stop content farms from getting top listings with “shallow” or “low-quality” contents.
This update affected about 12% of its search results in the US. Moreover Google was pleased with this move because it obtained a greater impact on results as compared with other previous algorithm changes.
However many observers believe that Google’s update is targeting both the content farms (those with shallow or low quality content) and scraper sites (those that copy others’ content). Google is not officially saying that their algorithm change is targeting at these sites. However later about a week after Google’s post, Matt Cutts who heads the company’s spam fighting team confirmed that their algorithm change which is targeting the scraper sites had gone live.
Google realized that it was a good targeted launch because very few queries were affected and a small number of search results change. This resulted for searchers to find sites with original content rather than scraper sites.