If you think you are stuck between a rock and a hard place with Cingular being the only carrier for the iPhone, guess again. The Consumerist gives some excellent tips on how to make the switch from other networks if you want to purchase the iPhone by June. They are definitely not pushing Cingular since they say this (too funny!).
"Bear in mind we are not advocating that you switch to Cingular, a service which has tendency to suck and hate its customers"...
Go to iPhone is Cingular: How Do I Switch? for step by step instructions on how to make the big switch.
Want to know how others feel about this issue? When visiting Macworld we asked a few people how they felt about making the switch to Cingular.