Kattack Mobile allows you to use your IPhone in place of a Kattack LIVE Tracking device. You can join a race feed and have your track recorded in real time. In order for the App to record, you must first join a LIVE race which typically is set up by the event organizer. Kattack Mobile works even if there is no cell coverage. It saves the track points and uploads them when back in cell range. For more info go to kattack.com. Kattack Mobile requires version 4.3 of iOS and later because it uses background mode.
Disclaimer: Continued use of GPS running in the background can dramatically decrease battery life.