Good point. And not that Perez Hilton should by any means be a gauge for all websites' traffic, this is telling:
"The analysts at Hitwise claim that celebrity gossip blogger Perez Hilton now gets more traffic from Facebook than from Google – more than 7 million pageviews from Facebook alone."
http://www.copyblogger.com/facebook-killing-seo/
Essentially, depending on your (or your clients') business, product, and industry, it may be smarter to optimize for Facebook (or any other site, for that matter) than Google. It all goes back to that big Marketing question: who is the target audience and where do they live?
