Bartlett Publishing has put together several lists of books available from many various publishers which are essential reading for anyone interested in the topic. Check them out today!
You can view the articles from the blogs which preceded these at the following URLs:
Todd Wood has an excellent introduction to the form-vs-function debate, focusing on the ideas of Richard Owen. From his post:
Owen's eclectic embracing of functionalism and structuralism were answers to different questions: 1. Why are organisms so well-adapted? and 2. Why are there homologies?....Organismal similarity was to Owen based a [sic] natural law of the archetype. The differences Owen attributed to functional requirements. (Thus he saw two answers for two different questions.)