Mark Rittman, co-founder of RittmanRead, has just released his book on OBIEE 11g! It has been a long time coming, but well worth the wait. This is not just a "warmed over" documentation book, this book has alot of valuable information and is a must buy for all OBIEE 11g developers. This is one book that covers it all. Not only installatlon of the various configurations but also covers all the topics for the developers as well. Mark does a very good job telling what needs to be done, but also describes what is actually happiening under the covers. The most recent version of the software, which just came out, is also covered along with a separate chapter on Oracle Exalytics. The book is large, over 1000 pages, and should be included in everyone's tookit.
I particularly like the ebook edition so I can carry it on my ipad where ever I go.