Facebook has lunched recently updates to the Comments Box plugin which will enable user to comment on your website and will include moderation tools and distribution.
What does it mean for the online anonymity? Now your comments anywhere on the web might be not only posted on your Facebook page but traceable and perhaps stored somewhere. And I am sure that a number of 3 letter government agencies will have access to that records.
Interesting to see how many websites may adapt this plugin.
Source: Facebook Developers blog