Here's all I have seen...
• Ed Eberlein did one called Arizona Trails, in conjunction with KXCI. They were pretty good, but only posted 10 in 2007, and then they stopped

• In 2005 Deborah Lee Soltesz started one called "hiking with deborah" on Arizona as well, mostly on trails in the Flagstaff area. But after 11 episodes it stopped as well.
• The National Park Service has one called "Hiking Grand Canyon"...done a few episodes this year, but not very much.
• Likewise, the Arizona State Parks have one called "Arizona State Parks update". They started it in 2007 and since this year put an episode out every 2 months or so. It was what tipped me off about Suvoyuki Day at Homolovi Ruins in July, which was awesome, and when I was there the guy who produces their podcasts was finding out from people leaving how they found out about the special weekend. When I told him the podcast he was encouraged.
I've even wondered if it might be possible to have different people in the HAZ community contribute to making episodes and getting a podcast going from those...although I'm not really sure if there would be enough interest??