Since I know a number of runners use the iPhone for tracking the distance of their runs, I thought I'd send out a review of the MotionX-GPS app that is available for all iPhones. I've tried this out and it's absolutely fantastic if you are looking for something that you can use for tracking the exact distance of your runs. I found it as exact (and if running in a wooded area, more exact) than any Garmin running device.
The functionality of this app is way ahead of the curve. It integrates with your iTunes library and lets you use your songs, playlists, etc. as well as use the pause, play, skip forward and skip back of all your sings.
You can record pictures, if you are into that sort of thing, at different points of your run.
The one function that blew me away was at the end of my run. I was able to send to my Facebook update a map (that all of my friends could view) of my run.
If this app had a heart rate monitor with heart rate ranges, I would recommend this as a replacement for the Nike Plus system on the iPod.
I have two criticisms of it. The first is the number of runs you can store on it. But seriously, after ten runs, you should be logging the runs in your running journal but it would be nice if it had an on-line page/site to do it.
My biggest criticism, and why this wouldn't replace my Nano or iPhone is that the app, like all GPS apps on the iPhone, is a battery hog. I haven't gone more than ten miles with this on a run, but it ate 60-70% of my battery in that hour and a half. I question if it would last for a half marathon race, and know that a marathon is out of the question.
If you are looking for such a GPS tracking system for your run (that are less than 10 miles) that doubles as an iPod, look no further, this is it. I give this app 4.5 out of 5 stars, and only hold off a perfect score because of the battery and heart rate monitor functionalities.