Although these aren't truly typography books, I have found them to be particularly useful and indispensable, so I'll mention them (and am prepared to be punished for going off topic
):
1. A Designer's Guide to Adobe InDesign and XML by James Maivald and Cathy Palmer (ISBN 978-0-321-50355-8). With ebooks gaining increasing importance, a designer really has to have some idea of how to deal with XML. I'm so old (let's just say I can remember the Dwight Eisenhower presidency with remarkable clarity) that dealing with such things as XML is like trying to deal with a foreign language. This book does a good job of introducing XML without trying to turn me into a programming maven.
2. Adobe InDesign Styles by Michael Murphy (ISBN 978-0-321-60606-8) provides a comprehensive look at styles, which are the foundations fo good typography in InDesign. Although other books, such as David's Real World InDesign CS4, introduce styles (and do a very good job at that introduction), Murphy's book gives that comprehensive look. I found it to be a real lifeline when I switched from Ventura to InDesign CS4 and needed to reestablish a workflow for books that began with author supplied Word and Excel documents.