It's been around for awhile starting in Germany, back in the early 1970's, and becoming more popular across the world in the 21st century. Garden Roads are a cool hobby, and it's a bit safer than hopping freights, although sometimes one wants a little extra excitement and danger in their lives.
Anyway, there is a dedicated YouTube page to Garden Railroads in Minnesota, run by the Minnesota Garden Railway Society. You can see cool videos of these garden trains there:
http://www.youtube.com/user/MGRSClub
For those that are curious, Garden Railroads, or "G-Scale" is about twice the size of the familiar O-gauge Lionel model trains that many had as kids growing up. The track is two-rail with about 1-3/4" width between the rails. It is the largest of the model electric trains, and the smallest of what is consider "Large Scale" trains.