I'm not sure how long this has been around (I live in a cave most of my life) but this Downhill Mountain Bike park
(click here) looks totally awesome!
I was there this past weekend, and saw the jumps first hand. They look very well setup and spaced well so that you can "safely" grab some major air.
I checked out the rental bikes, too. They are amazing. Very light weight, disc brakes, and a suspension that would put most street bikes to shame!
Looks like a blast!