Almost a year ago, I reviewed MotionX – GPS for iPhone. After using MotionX for over  a year now and after upgrading to iPhone 4, it’s time for an update. First and most important is battery life. With iPhone 3G, my battery would barely make it on a 3-4 hour ride. Now, with iPhone 4, I can easily ride or ski 4 hours and still have 60% battery left. Also, after a year of using the MotionX GPS for tracking ski tours and mountain bike rides, I have found it to be VERY accurate. And finally, since MotionX can export or import .gpx files ( the standard XML format for sharing track data between GPS devices), it’s easy to share trip data. Thanks to MotionX, I no longer carry a GSP: I only carry my iPhone.