Final Jeopardy: Man vs Machine and the Quest to Know Everything by Stephen Baker
I found the Watson exhibition very exciting. I was therefore eager to read Baker's new book, Final Jeopardy, that accounts the inception of IBM's Jeopardy Grand Challenge and the software team that completed it by creating Watson. Although light on technical details, the book provides a good overview of the primary challenges. It also discusses the non-technical issues that the Watson and Jeopardy teams struggled with in staging the man-machine competition. Overall, a very good and enjoyable book. If you enjoyed Baker's Numerati, you'll probably enjoy this book too.
The next challenge is to create a computer that can write Jeopardy questions rather than just answering them.