Sure, its only $450 to some but it sure is a lot of money to one who is but an photography enthusiast. So, I jolly well do a bit more research before I dive into the world of flash photography.
Here's the good news I found so far - our Nikon D90 is capable of updating the Nikon DB-900 with the latest firmware. Secondly, on say taking a photo with the Nikon D90 with a F/1.8 lens, the AF Assist Illuminator of the Nikon SB-900 can now reach up to 10m! Excellent!
And from my latest review of the Nikon SB-900 user manual (you get the hint?), it matches a typical compact camera user manual in terms of thickness. That's how sophisticated this flash is. It's almost mind-boggling to try to absorb what this flash is capable of doing!