An iPhone user who is so focused on their app, texting or finger caressing in a public place, that their gait is slow and erratic to the point where you're in a quandary about their living status.
Trying to negotiate a supermarket aisle either on foot or with your cart, to be blocked by a slow shuffling individual - the iPhone Zombie - who, upon passing (eventually), is seen to be caressing their iPhone.
"I'll be right over, as soon as I negotiate the path around the iPhone Zombie"
"Watch out! iPhone Zombie on the road!"