The book is a fun read, a great overview of the history of search companies with some interesting thoughts on the future of search.
The last chapter, Perfect Search, looks forward to the next-generation of search engines. It has several pages on clickstream personalization. An excerpt:
Perfect search ... means nothing if the engine does not understand you -- your likes and dislikes, your tendencies and tics.Current search engines treat each search independently, ignoring the valuable information about what you just did, about what you just found or failed to find. Paying attention to that clickstream will allow search to become more relevant, more useful, and more helpful, all with no effort from searchers.
A solution to this problem lies in the domain of your clickstream. Through the actions we take in the digital world, we leave traces of our intent, and the more those traces become trails, the more strongly an engine might infer our intent given any particular query ... I expect those trails ... to turn into relevance gold ....
Clickstreams can provide a level of intelligence about how people use the Web that will be on an order of magnitude more nuanced than mere links, which formed the basis for Google's PageRank revolution ....
Clickstreams are the seeds that will grow into our culture's own memex -- a new ecology of potential knowledge -- and search will be the spade that turns the Internet's soil.
Engines that leverage clickstreams will make link analysis-based search (nearly all of commercial search today) look like something out of the Precambrian era ... We have yet to aggregate the critical mass of clickstreams upon which a next-generation engine might be built ... [but] we're already pouring its foundations.