
The Lost Worlds of 2001 is a 1972 book by English writer Arthur C. Clarke, published as an accompaniment to the novel 2001: A Space Odyssey.
I think Kubrick was very much the dominant force in the partnership, but they did work quite closely together.
(I think that's in Lost Worlds of 2001, which is a fun read)
“And because, in all the galaxy, they had found nothing more precious than Mind, they encouraged its dawning everywhere. They became farmers in the field of stars; they sowed, and sometimes they reaped. And sometimes, dispassionately, they had to weed.”
http://en.wikipedia.org/wiki/The_Lost_Worlds_of_2001
I found one at a used bookstore ages ago and it was a fascinating look at the partnership and conflict between Kubrick and Clarke as well as a look at the different ideas and plots they discarded.
The concept is from a short story "The Sentinel" by Clarke.