Yes. They are pretty damn fun. For a nice loop, take the trail towards the Kids Klub campus at Whiteface (pretty nice grade, couple of stream crossings, big climb towards the end), and then the trail that starts above the Kids Kampus parking lot down to where you were (nice singletrack, a couple of stream crossings, nice downhills). Then there's a cool, mellow singletrack on the right side of the main trail as you're coming back to the parking area. The really hard trail is called "Rock Garden", and that had me off my bike for a lot of it (although I'm a lot better now, and I'm itching to try it again).
For a map, there used to be one at the entrance to the trails (just past the Hungry Trout restaurant on Route 86). Or you can check here. Or, if you want to do the local crew a solid, you can join the Barkeater Trails alliance, which is trying to turn Wilmington into a Mountain Bike Destination - Similar to Fruita, Colorado or Moab, UT. I gotta say, that would be pretty cool . . .