I now notice that Åmazon literally has dozens of "how to" specifically for the D90. But if jr says this is a good one then I'm going to wait.
As to this specific Nikonian book amazon.com like B&N has reviews, used ones for sale (at a higher price than new ones) and some new ones from third party dealers.
This all strikes me as really strange. I am used to books "slipping out" often from review copies and someone gets greedy and tries to sell it for more than new because of antipated demand but this is absolutely crazy. Anyway if you want one right now it would appear you could buy a brand new one from amazon.com.
Given my (lack of) love for amazon i plan to wait for three weeks until B&N ships mine.