There have two developments in Google search which have bearing for SEO in 2011 : first is improved spam detection and the second is PageRank changes.
Battling Content Spam
On 21 January 2011, Google announced a redesigned document-level classifier to detect web spam. This will detect pages with scraped content using bots or software, or manual spam content, such as repeated keywords words which occur in junk, automated, self-promoting blog comments, or sites created for link exchange. This will affect primarily sites that copy others’ content and sites with low levels of original content.
Google also claims to target “content farms,” which generate content for SEO based on keywords. These employ low-paid content creators, who scrape content from high ranking sites. However, certain sites generate high revenues from Adsense for Google, and experts doubt if Google will black list sites like eHow, LiveStrong.com. AOL, with Seed.com and Yahoo, with its Associated Content , are also in the content farm business.
Content scraping, and pingback spam are some of the biggest threats a genuine site faces in 2011. There are tools for pingback spamming and content scraping. Solutions are: check pingbacks before approving them; you can report any scraped content to Google, Yahoo and Bing. Auto blog pingback spam is now so bad that many blogs are refusing to accept any pingbacks at all. This is due to many unethical sites that create blogs using packages of WordPress plugins that copy content from other blogs or article publishing sites, and send pingbacks to many blogs to try to get backlinks and traffic.