Only one train at a time John and limited to 5 of each car type. At this point, he's trying to gauge interest and see how much work it will take to support, especially if he adds multiple trains and more engines/cars. Personally, I would love the option to run multiple trains with more cars, but am somewhat ambivalent about the specific engine/car designs. For me, multiple trains in different colors would suffice for checking out a layout design though I wouldn't complain if I could throw a smoking Big Boy on just for kicks. 
EDIT: And I should add that I'd be willing to pay for them if the price was reasonable and it helped keep the basic program freeware.
