My wife has an ipone and decided to download the $10 application to it the other day. The features for 'paperless' caching and finding spur of the moment caches near you was really really cool. I'm thinking I'm going to get an iphone now. I didn't attempt to use it as the gps though. I've had a Garmin GPSMap 60C for a few years now and love it, especially after adding the street maps to it. I will have to get out and try usuing the iphone for geocaching and see how close it gets me relative to my gps. Otherwise, the program on the iphone does most of what the geocaching wap site does, if not more being more interactive. One problem though with the ipone application was that we were logging cache finds from it, but when I got home to check my finds page on the website, none of the logs registered on the site. Not sure if this was a one time problem, or if it's a glitch in the software.
I hope this helps.... :-)
Grimmie895