aristotle - 8:21 pm on Dec 26, 2011 (gmt 0)
There's something else I should have mentioned. Back when the +1 button first became available, some people said that Google might demote sites that don't have it installed. Some even said that Google was using this possibility as a threat to try to pressure site owners into installing the button. I never believed any of this myself, but think I should mention it here because at that time it was being discussed.