I've always been skeptical of step-counters, but the built-in GPS support would HUGELY increase the accuracy of calorie-burn estimates.

$249 for 8GB base device.

MOTOACTV compiles data and attaches it to your music, then harvests it to create a “high-performance playlist” of songs

that’ve statistically made you move faster, and with more stamina than the others in the past.

OOOH. That's cool.

Heart rate monitoring is an accessory, not built in. Wrist strap/arm band are extra too.

Oh, here we go: MOTOROLA SF700 Wireless Sports Headphones with Integrated Heart Rate Monitor