Rand’s recent WBF about co occurrence was a real wake up call for those still transfixed with link building practices of old. While anchor text based links may still have some effect there is little arguing the fact that the factor’s importance is dwindling. In its place are things like social signals, link age and most importantly a growing reliance on relevancy and how that is deciphered.
For those that haven’t read it yet, I wrote a piece a few weeks ago about what I felt recent Google penalties are really trying to solve. My view is that Google is really trying to clear up the link graph and with it valueless links so that it can clearly understand relevance and associations again.
It’s something that web ‘creator’ Tim Berners Lee first wrote about back in 2006 in this magazine article and Google has been talking about ever since, ploughing lots of cash into acquisitions to get it there.
So, why invest so much time, effort a resource into such a game-changing project? Quite simply because its existing keyword based info retrieval model is in danger of being bettered by semantic search engines.
To understand why this is the case we must first delve into semantics and why it changes the way search engines work.
Source : http://www.seomoz.org/blog/semantic-web-and-link-building-without-links-the-future-for-seo