Introduction to Information Retrieval by Chris Manning, Prabhakar Raghavan and Hinrich Schutze is a recently published IR text that covers state of the art methods of indexing, retrieval and ranking in the context of modern search engines. This book is available at the CU bookstore or for purchase on-line.
Note that the PDF for the entire book is available on the book's website for free. I'd encourage you to go ahead and buy the printed book anyway. In past years, folks who bought the book were more likely to read it (and did better on the quizzes).