Not exactly a backcountry festival, but indiative of the growing numbers in Colorado who are doing uphill skinning, alpine touring, hut tours, etc.
"The Aspen Skiing Company in partnership with the City of Aspen, is hosting an uphill event [on March 31]at Buttermilk Ski Area — AT skiers, trail runners, snowshoe-rs, split boarders, hikers and all non-mechanized uphillers are welcome."
Looks like fun. Hourly workshops. Coincides with the Cliffhouse Full Moon dinner, up top.