@jholcomb - I don't know about other parts of the country, but I lived briefly in Southwest Georgia and it was pretty common there. Natural gas is definitely better for home use in many ways--it burns hotter, for one--but not everyone has access to natural gas. And a lot of people like gas for cooking and running a fireplace.
The house I lived in down there had a 500 gallon liquid propane tank buried in the front yard. (LP tanks can be safely buried, unlike oil tanks.) That's unusually big; the original owners of the house had wanted to run the water heater and the heat from LP as well as the fireplace and cooktop. People that just wanted to run a fireplace and maybe a cooktop sometimes had small tanks in their garage.
My favorite thing about having the tank was that we had the gas grilled hooked into it, so we never had to worry about the cylinder going empty. (I guess our tank could have run empty, but the local utility the the gas came from checked it quite often.) I also liked that it was a local company; I taught the owner's daughter in my class.
The worst part was we had a leak. Fortunately, it was outside, so it wasn't a danger to us. Unfortunately, that meant we didn't smell it until it had leaked hundreds of dollars of gas!