First, Google actively participates in the "science" of technology and often shares their knowledge by releasing papers from their R&D department. You can find those papers from the reference link below. I haven't searched for specific papers on search retrieval algorithms but there should be more than enough information available on the subject from a very technical perspective, as well as papers on storing massive sets of data and effectively querying it.
Publications by Googlers
Other than Google's resources, I highly recommend that you look into Semantic Web research. Semantic web isn't a method of searching data and even though the concept at first seems a little vague, the clear implications of a semantic web "engine" would be to parse the information within the WWW and link relevant information with one another.
In short, semantic web is the science of what many forward-thinkers hope and are working for the internet to truly become where the information that is provided is well parsed, interpreted and correctly linked together. I haven't looked into it much myself, so some of my information may be a bit incorrect. However, their are plenty of resources available that discuss semantic web and many are hoping/waiting/working on a break through within the field with the hopes of making the "next big thing" for the internet.
A good starting point for learning about semantic web is, of course, Wikipedia.
These references may not be books but it is a lot of information. Reading and sifting through all of the technical information should keep you busy for a while.
