I have MapMyRun installed on my Droid. I've used it several times at the same time as my Garmin, and it's close, but always a bit off. The Garmin is definitely more accurate. For example, on a recent run, the Garmin measured 6.0 miles while the phone app measure 6.12 or something like that. When looking at the maps they recorded, the phone had me jumping all over the road. It looked rather as though a dog had been wearing it. That being said, being a tenth off per six miles isn't THAT big of a deal.