Google badly needs to evolve their algo beyond the current dependence on backlinks, and I'm certain they are working on many fronts to do that.
I've been thinking about this for a short time, and am starting to wonder if Google is backing out of "Backrub" bit by bit due to the SEO world manipulating rankings because of linkings. I see this happening through the NOFOLLOW movement on paid advertising, as well as not being able to purchase links, and google frowning on link exchanges. I do think they are starting to put more weight into relevancy, such as Wikipedia, because it's ALOT of content on one single page per topic. (granted there are the one-offs of incorrect data or vandalism or whatever... just to pacify those that say Wikipedia isn't a resource because of yada yada..) but as a whole, quite a bit of info. I think also (speculation) that because of the power placed into linking as a result of Backrub, Wikipedia added the NOFOLLOW to prevent spamming. Eventually, links may very well become an SEO myth, but ehh, what do I know?