The web version (free) of The Data Journalism Handbook was released today. An ebook and a print version will be available soon from O’Reilly Media.
Web Version: Direct to Full Text
From an Introductory Blog Post:
The handbook is a free, open source reference book for anyone interested in the emerging field of data journalism. The book will be made freely available online under a CC BY-SA license so anyone can read, copy, share, redistribute and reuse it under the terms of this license.