Manning also have a book on Lucene, the library that powers Solr and ElasticSearch. IIRC the book covered how Lucene actually works under-the-good and would therefore act as a good reference on the subject in general.

Taming Text is about building a question-answering system; it came out about the time Watson came online; it's not a plan, rather a cookbook of experiments using Apache products like Solr and OpenNLP, but is a great tutorial on how question answering works.