Microsoft SQL Server 2008 Internals finally starts to roll off the presses at Microsoft Press today! For me this is the first time in print (in book form at least) and my consistency checking chapter (about 1/10th of the book) represents a complete brain-dump of everything I know about how DBCC CHECKDB works.
Kimberly also wrote a great chapter on index internals with some nice examples of how and why they're linked together the way they are. And of course the rest of the book is excellent too, mostly by Kalen but with additional guest chapters on the query optimizer by one of its architects, Conor Cunningham, and on tracing and auditing by fellow-MVP Adam Machanic - all good friends of ours.
Check it out on Amazon.com here.