I've got a couple of the Smashing books now and they've always proved to be really useful. They're not best-suited to beginners, as they usually assume some prior knowledge of the subject, but if you're ready to take your abilities to the next level they're great. Smashing Logo Design keeps up the standard although it's slimmer than some of its shelf-mates. It's not a practical guide to Photoshop techniques, although they're included, instead it distills ideas from various areas to suggest an overall strategy for designing effective brand identities.
The book first breaks down logo design into its various types -- wordmarks, letterforms etc -- and the reasons you might choose each style. Then the individual disciplines needed for the actual design are covered including basic conceptualisation, font and colour choices, presentation to the client and even what file-types you'll need to supply in the finished package. However, Smashing Logo Design is intended to be as much inspiration as instruction because almost a third of the book consists of a showcase section, featuring hundreds of finished logos you can browse for ideas. It's not the cynical page-filling ruse it might sound - they make a valuable source-book of ideas and techniques for when you get stuck without that first spark of an idea. All together it's a well-focussed and helpful reference not only useful for graphic designers but also for potential clients who want to ensure they get the best logo for their projects.