AT&T making out like bandit on iPhone

Apparently AT&T is making out pretty well on this whole iPhone thing. According to a Rubicon Consulting study (NYT link, registration required) of 460 iPhone users about half (47%) switched to AT&T to get the iPhone and agreed to pay an average of $19 more per month to use the iPhone over their previous cell. Those numbers are just about right in my case from when I traded in my Treo on Sprint.

What about you guys? How many of you switched to get an iPhone and how much more are you paying per month than you were before?

[via iPhone Central]