Jacqui Cheng reviews the new iPod nano:
I’ll cut to the chase: Nike+ on the new iPod nano was not particularly accurate for me on speed or distance, but the poor speed calculation is likely because of the inaccurate distance estimate. On the three runs I did with the nano, Nike+ over-estimated my distance by about 25 to 33 percent. In some cases, that added up to more than a mile of extra distance. The nano did keep the time correctly though—this is the easiest part, of course—but because of that, the data on how fast I ran was grossly over-estimated. (I sure would like to believe that I can put away 5 miles at 7 minutes per mile, but it just ain’t the truth.)
Too bad. If it was accurate, the new iPod nano would be even better for runners.