(edit: stevenyc beat me to it)
The do quote him about 30 times in their pubs (I just looked this up the other day), but 90% of the quotes are from his book Cosmos and I think the quote says something along the lines of the evidence supports the existence of an intelligent creator.
Based on the 2 other books of his that I have read, I cant really see him making the statement that they quote without putting some sort of qualifier around it. I have not had a chance to read Cosmos yet, but its next on the list after "End of Faith".
At any rate, here are the notes I quickly jotted down when I looked this up the other day (as far as where Sagan is quoted by the WTBTS). They are hardly detailed.
Why worship God - Cosmos, Carl Sagan, 1980, page 21.
Survival book - chapter 1
Creation book Chapter 5 cosmos
Chapter 8 cosmos
Chapter 9 Cosmos
Chapter 14 Cosmos
True Peace book - Chapter 2
Reasoning book - Evolution heading -cosmos
Life Heading heading -cosmos