Found a Disc golf app for the iPhone called Frisbee® Golf on iTunes. It's $2.99 ^_^
Autonomous Productions is developing a game in partnership with the PDGA. It will be available through Wiiware download service. There currently is no release date but they're targeting early fall '08.
I have this game for Window Mobile on my phone. I think I paid about $10. its fun but you have limited options for pointing where you want the disc to fly.