Well, one book: Beginning TiVo Programming which will street on February 12, 2007. This book is a comprehensive guide to programming TiVo HME applications, and it is the first book of its kind. One of the authors, Kyle Copeland, is connected through my circle of friends and I got a chance to chat with him for a bit at CES. The authors are the guys behind AudioFaucet, the HME application that won TiVo’s contest. They had to suspend work on that while working on the book, but they plan to resume work on AudioFaucet. I think this will be a good resource for any HME developers.
The other publication is a digital download: Coping with TiVo: Opportunities of the networked digital video recorder It appears to be an industry research report.