I am spending an afternoon building this app. Follow my progress here and on my blog at kilovolt42.com.
This source code is released under the MIT License.
kilovolt42/Geoambulate
Geoambulate lets you set goals for Earth based distances you want to virtually walk (say from NY to LA). View your progress on a map and receive a notification when you achieve your goal. Read blog posts about this project at http://kilovolt42.com.
Objective-CMIT