aristotle - 3:16 pm on Jun 16, 2011 (gmt 0)
I'd guess that the +1 Button gets put up against this sort of thing. Maybe. The "block site" option applies to the entire site, but the +1 is per-page, so I don't know...
Most likely the +1 Button will create the same bias in the SERPs as the Block Site Feature. That is, it will tend to hurt the rankings of websites that express minority views. This is because, being in the minority, these sites won't receive as many +1s as sites that express majority views, but will get more Blocks.
But Google is adept at spotting different signals in different verticals and makes allowances depending on topic. My guess is that in the case of the political arguments these signals wouldn't be used to affect the rankings while perhaps retail sites might see more impact.
I have doubts that Google can consistently make these "allowances", assuming that Google even tries. There are controversial issues relating to politics, religion, healthcare, drug use, abortion, the environment, corporate policies, etc, and for each of these issues there are numerous relevant keywords and key phrases. I think it would be extremely difficult for an algorithm to sort out when to make "allowances".