I read an article a few days ago (I forget the magazine, but it was a financial one.) In it they talked about the problem at&t is facing now...
They are raking in the money hand over fist as the only carrier to offer the iphone... but people are starting to get angry at the lack of coverage (What good is the phone if you can't use it) which we all know...
The real issue though is if they DO upgrade their network, they end up loosing out on the extra income the iphone generates.
So they're stuck- make money now, but risk loosing customers, or loose out on the advantage being the only carrier of the iphone offers in the first place, and upgrade their network.
The writer was theorizing that eventually the unlimited data plans are just going to go away as more and more people get smart phones, and eventually we'll pay for levels of service, just like voice. LAME.