My friend and colleague Peter Haber of the historical seminar at the University of Basel (and co-editor with Jan Hodel of the excellent blog Hist.net) has just published an excellent book that everyone who can read German needs to read: Digital Past: Geschichtswissenschaft im digitalen Zeitalter.
The book provides an excellent overview of the history of digital history and Haber does a nice job of summarizing a series of complex developments in a relatively brief narrative of the arc of our field. I particularly liked the sections devoted to the ways that searching behavior is changing historical studies and on data driven history.
My only complaint about the book is that Oldenbourg is not publishing it in English as well. At 150 pages it would make an excellent introductory work for advanced undergraduates or graduate students studying historical methods or digital history topics.