Andy_Langton - 11:29 pm on Sep 21, 2012 (gmt 0)
I would strongly agree that Penguin isn't a backlink thing. Backlinks just happen to be a very strong signal.
As for blocking referrers, this isn't going to affect the algo in any direct way, since Googlebot only sends referrers in a fairly small percentage of cases, so it won't have any idea that you blocked them. What would meet the requirement, I suppose, is the mythical 'disavow links' tool.