The shop is still open. The track is not. They built a new, bigger building where the old dirt track used to be. Its now called RC Hobby Barn.
www.rchobbybarn.com/
We are still racing on-road in Madison and there are a couple of off-road tracks around the area. Not sure on where they are since I'm an on-roader.
www.rc3racing.com<-- That is the website for the on-road club.
Hope that helps you out some.