I'm sure it's mentioned in Moon Shot[1]. Most books about the space race mention it. Houston was just one of several proposed locations which met NASA's official specifications for a mission control site.
One of those specifications was the minimum distance between mission control and the launch site. That specification was revised upward so that it just barely excluded the then-leading site after Rice University agreed to donate the land. It doesn't take a Von Braun to figure out what happened.
That's completely different than what the other poster (Symmetry) claimed -- that they otherwise would have been in the same location.
That politics plays into the decision making process of which site to use isn't too shocking, but Symmetry was claiming that the very creation of that site was political.
Reading wikipedia, I get a fairly different story. I did a short search for other versions, but mostly just found inaccurate yahoo-answer type sites.
http://en.wikipedia.org/wiki/Lyndon_B._Johnson_Space_Center#...