The 2nd (1st open to the public) Fat Bike Summit is happening this coming January down near Yellowstone. You can look at the schedule, and all the other beta, here.
I’m on the fence about attending, mainly because I have mixed feelings about riding on snowmachine trails around here. Without fail the sled guys were courteous all last winter, but I often found myself skiing instead, to get away from the noise. But I’ll probably go.
What would be really interesting would be a 3 day hut trip on the southern part of the Big Sky Snowmachine trail; doing a car spot, and staying in the Wapiti and Cabin Creek cabins. The ungroomed stretch between the two cabins might not be rideable a lot of the time, but under good conditions would make for amazing riding.