In early November Google promoted their ability to execute AJAX/JS to index some dynamic comments. A few years ago, Jed Singer and I did some digging to see just how well Facebook pages were crawled and indexed. The answer – not very well, but Facebook still enjoyed decent rankings for profile and brand pages alike, despite spidering issues. Our review suggested a heavy dose of domain authority and backlinking signals, and not necessarily on-page relevance.
Then, suddenly, Facebook pages started to show up less and less (somewhere around the time “Google Me” was the rumor) except for specific people and brand searches. I assumed a manual algorithm tweak to clean up the search engine result pages, and make general Facebook pages less of a player. The same kind you saw with Digg pages, Amazon subdomains, etc.
But when I read that Google is getting better at interpreting Facebook comments, I assumed they also got better at reading all Facebook’s public tabbed content. Still, I assumed they wouldn’t change their algorithm suppressing Facebook rankings.
Wrong…

This is one of several examples I found. It worried me about my long-tail for my websites, and sure enough, Facebook SERP SPAM there too. I don’t know if Google took their eye of their algorithm and made some changes without considering their prior intention, or if this is a real decision (can’t imagine why, though). I expect it won’t last long.
In the meantime, black hats will go at it, and white hats (and shoppers) will need to be annoyed by it. What a thoughtful holiday gift, Google!