I'll have to check out that app, my husband likes My Tracks. We used it on our Tuscany cycling trip (for walking, cycling, whatever) and he had all kinds of nerdy stats.

I saw the way the iPhone gets the HRM data is via a receiver for standard ANT+ heart monitors - see http://www.mapmyfitness.com/shop/fitness-sensors.html. A quick google shows the bluetooth is actually built in to the transmitter, so you're limited to a few brands (though it looks like one of them is Polar, so maybe we can look forward to bluetooth transmitters for other Polar tools, like the cadence and stride sensors?) http://www.allaboutsymbian.com/news/...opens-buy_.php.

I have found the GPS on the phone to be less reliable than a computer (and actually less reliable than my Polar GPS unit) especially as the weather gets crappy, but it is a useful tool for goals and stats (that's what my husband uses it for, anyway). I think to check it as we go he just taps the screen, but that probably means he has to unlock it. Maybe you could use an app that speaks info to you when you hit certain milestones?