For the record, the Google exec (Berthier Ribeiro-Neto) is the co-author of "Modern Information Retrieval" [1], an excellent book and close to a standard text on IR.
I can second the recommendation of that book, I've heard a lot of good things, though I haven't read it. It's recently been updated in a 2nd edition [1], though I have no idea if there are substantive changes, presumably, there are, given more than a decade has elapsed. If anyone's read the updated version, I'd appreciate knowing if and/or how the book's changed, I've been thinking about picking it up.
I have read pretty big sections of Manning's Introduction to IR, and it served me fairly well as an introduction to the field. It's available online.[2]
[1] http://www.amazon.com/Modern-Information-Retrieval-Ricardo-B...