From the link Dan Yeruski provided: http://www.sltrib.com/outdoors/ci_12715936
" Another increasingly popular alternative is to purchase a propane fire pit, some not unlike gas logs popular in homes. Two Utah companies, Camp Chef in Logan, and Wheel Campfire in West Valley City, produce fires fueled by traditional propane tanks. Wheel Campfire also offers accessories that include heating racks for Dutch ovens and a wok.
While these propane fires don't provide the smoky ambiance of a traditional wood fire, they do offer advantages. They are legal during fire bans and light instantly on cold mornings or when the weather is bad.
'If it has a valve and when you turn it off it goes out immediately, then you are okay [during a ban],' said Reid Shelley, assistant fire management officer for prevention for the Wasatch-Cache-Uinta National Forest. "
... probably a bit too heavy for backpacking