Google is indexing facebook comments for PageRank
http://www.netmagazine.com/news/google-indexing-facebook-comments-111529
Google has tweaked its “googlebot” so that it can now parse Ajax/JavaScript content, meaning that it can now index some dynamic comments from websites like facebook. Some websites will likely benefit from this feature, since having their comments appear in google search results could drive traffic to their sites. However, users could also be repelled by google results containing spam comments, so websites may have to become more careful with moderation. It is not yet known how google will deal with comments that have been duplicated across several sources. Potentially, the new algorithm could penalize websites for having fewer original comments.
Some experts wonder whether users actually want to see comments appear in google search results. Some users are already off-put when results from content farms (such as e-how) appear. Some facebook users also may not be pleased with the privacy implications of having comments appear in search results.