The challenge Google faces on how to improve the way users retrieve information from the web is actually limited by its own search interface. Google's simple search box interface has successfully trained most users to abstract complex queries into few keywords, and as result, much context are lost as we are searching. In some way, Google Instant is a way to mitigate this problem by previewing results per keywords, but the search experience is still limited to a keyword index, regardless the interface Google wraps around with.

What's interesting moving forward how AI can help search is about how NOT to discard the constraints of human language. In ML, constraints are good, and for search, it can help the indexer to more intelligently quantify the n-grams. End of day, human being still converse in sentences, not keywords.