If you only read one book on intellectual property (a huge area that includes copyright, patents, authorship, commons, trademarks, and trade secrets) it should be Debora J Halbert's Resisting Intellectual Property Law (Routledge; 2005). Halbert's text is clearly written, extremely well researched and provides clear examples of the mess into which unbridled property rights has delivered us in the early 21st century.
Resisting Intellectual Property Law attempts to build a theoretical base for the commons. In doing this Halbert develops a strong critique of Habermasian public spheres. I have long been suspicious of Habermas' modernist and bourgeois obsessions and Halbert articulates these "anti-democratic tendencies" (24) far better than I can.
The text goes on to look at End User Licence Agreements versus Open Source. The realities of digital music distribution, and the morality of patents and medicine. Interestingly, the illegal distribution of media is so often portrayed in moral terms by those parties attempting to enforce copyright to texts. Finally the patenting of genetic materials (i.e. the human body) and the ownership of traditional or indigenous knowledge is discussed.
I am only a 1/4 of the way into the text, but not since my first encounter with the works of Lawrence Lessig have I read such an accessible and compellingly argued book on intellectual property. The contents are:

-- Theorizing the public domain: copyright and the development of a cultural Commons
-- Licensing and the politics of ownership: end user licensing agreements versus open source
-- I want my MP3's: the changing face of music in an electronic age
-- Moralized discourses: South Africa's fight for access to AIDS drugs
-- Ownership of the body: resisting the commodification of the human
-- Traditional knowledge and intellectual property: seeking alternatives.