We both have Iphones. I did download the Wherigo app. We haven't tried it yet. We thought maybe that it just is information about the Wherigo caches. Didn't know much about it but heard about 'cartriges' and needed a Garmin or pocket PC. We hadn't heard about using the Iphones instead of a Colorado/Oregon Garmin to find them. We will check it out this weekend and see if it works. There's a local Wherigo cache series about statues that we hope to test it out with then. We may not have to go with another Garmin if that's the case.
From what we've read we see a similarity between the Wherigo interaction with the app as kind of similar to the new Adventure caches? Kind of sensing when your device is near and opening the next part of the cache quest up. We've done the Adventure caches and enjoyed those.
*Crossing fingers* Thanks for that information.