A recent patent filing—well, recent in the sense that is was just published, but was actually filed last year—shows some sort of exercise progress meter + iPod contraption. It’s sort of like the Nike+ deal, yes.
The handy drawing pretty much describes what Apple is going for. You’ve got a treadmill, you plug in your iPod (or whatever deice), and then any and all data is recorded onto said iPod. That way you can keep track of how far you’ve run, how many calories you’ve burned, etc.
Something to keep in mind is that companies file patents all the time, and they don’t necessarily turn into actual products. So Apple could have filed this patent one year ago, then sometime last March said, “Ah, screw it. We’re not making that.”