You can get an ANT+ dongle to pair an iPhone with any ANT+ compatible HR strap.
The issue with using a phone is battery life. Once you turn the GPS on, you're looking at maybe 4-5 hours. Driving a peripheral off your phone would kill the battery life even more. I like iMapMyRun for walking, but if you're going to do something other than walk for a couple of hours and then immediately plug in your phone, you could wind up incommunicado.
Last edited by OakLeaf; 01-25-2011 at 06:34 PM.
Speed comes from what you put behind you. - Judi Ketteler