Search optimizers and Google's 'answer' strategy have made search links irrelevant. Read this blog post by Peter Yared on Digital Media.
The most interesting aspect of Google's move, however, is its tacit acknowledgement that its stalwart search links are largely irrelevant and might as well be replaced with social results. Google search results are essentially gamed results produced by search optimizers.
In other words, the search results that we supposedly value so highly are themselves paid placements, just like Google's keyword ads. It's just that in the case of search results, link owners have paid for SEO (search-engine optimization) to get Google's attention instead of paying for SEM (search engine marketing) to make Google give their links prominence. Either way, though, searches are mostly just producing ads by any other name.
In addition, Google's famed PageRank algorithm carries less and less weight these days, since fresh news and results inherently don't have as many inbound links as older content. (If it helps, you can think of PageRank as a kind of paleo-social search--just one that moves way too slowly for the modern Web.)
Via Heiko Idensen