You have to purchase an iPhone from Apple or AT&T before June (forget the exact day) to be eligible. Using a friends iPhone or getting one on eBay will not work.
This information is compliments of both an AT&T rep and AT&T Store manager.
I'm calling BS on this. The link clearly states BEFORE JULY 11, NOT JUNE. I just had my wife call the store I'm going to tomorrow and spoke with Jake and he verified that yes as long as you're a current iPhone subscriber you're elgible for subsidy. SOME reps are just spouting out things without even bothering to look it up, sort of like the rep I got this morning who wasn't helpful at all and I just let the call go