When people are taking longer than usual in the bathroom because they are waiting for people playing with iPhone's in the stalls. Often if people can't use their iPhone on the job.
The line outside the women's restroom was a mile long because of iStall.
When a car is way slow taking off at a green light because the driver is still text-messaging, checking email, playing Angry Birds or using other apps instead of watching the traffic.
I was only four cars back but ended up missing that light because three cars in front of me iStalled.