I had my first real descent this morning coming down from Jamestown into Boulder, CO. After a brutal climb (this was my first time in the hills), I was surprisingly fearless on the descent. It felt natural. I hit 48 mph.
I'm no expert but, keeping my body relaxed and finding a nice line to follow definitely helped. And try not to think about the concept that falling could easily result in death.
Edit: I was on a borrowed Giant OCR1. Solid bike for sure, but I imagine it would have been even better with a stiffer, quicker bike.