Google's statement could be a cultural / rebranding thing. I mean, could it be "search" = lost and then finds ; whereas "knowledge" = found.
The latter provides, perhaps, communication of the intent that Google already does the search first, not the visitor, and delivers the intelligence for knowledge on it's media real estate platform [ aka pages ].
Google already claims to know your intent. It responds with Google assets, lessening slots for SERP's and curtailing the long tail query with auto suggest that both controls and funnels the user intent. It has succeeded at removing many elements that make up SERP manipulation by site's to get a ranking advantage, in most key verticals.
I think the first level of that re-branding might be on a cultural shift for Google's staff as they tweak the algo's more along those lines. It may well be a way to differentiate their mission from Bing, and possibly other major players like Apple who may come more into the forefront with their own content enablement.
Maybe, over the coming months Google will talk more openly about this and we can see how it's manifesting itself. To be the central global player in knowledge would be a high ground advantage to take - if it can be achieved in marketing terms.