we stayed at Ilium last year and we made it to a # of Nightgrass shows and got home on the shuttle each night. I don't really remember past about midnight on any of my night in Telluride
but my wife swears they run late
The key is not to dilly around after the shows. We don't want 100's of people stuck in town, but we don't run the shuttles 24/7, either.
So, in short, yes...you can get a shuttle after the NG shows. But if someone decides to play till 2:30-3:00am you might have to decide if you are going to cab it and stick around for the end of the show or leave a bit early and get your free ride back.