A book I have enjoyed recently is the www wake series
http://www.amazon.com/WWW-Trilogy-Ro.../dp/0441016790
Which speaks about the development of an intelligence in the background of the internet, rather than something deliberately developed through human intervention.
What I found particularly interesting was the mechanism through which the human characters come to realised the increasing intelligence that it out there, coupled with the resources that the "intelligence" taps into to find out more about the world itself.
Might be of interest.