I thought a few people might want to see this example. I just traded my 2006 for a 2010 Tacoma yesterday. (at a Nissan dealer)
KBB- 2010-Retail 31,759. 2006-trade in Very good condition 17,023. Difference of 14,736.
What I actually paid- 2010- 29,491. 2006 Trade in Very good condition 15,500. Difference 13,991.
So, the aggregate difference is just about the same. I did better than the book by ~745 dollars.
So if you are looking for a current real world example, there you go. KBB is high, but seems equally high.