Yes, I believe you are right. What I heard is that AT&T (landline provider) will be reselling a prepaid service, not to be confused with AT&T wireless, but not actually provide the network that it will work on.
I've been hearing rumors that AT&T is starting up a new wireless division sometime this spring/summer. I've heard that Cingular could only use AT&T's name & logo in their advertising for 6 months after the merger for that reason. The rumor is that AT&T will be leasing their network through Sprint (although they will offer different equipment) and that it will be a CDMA service. Has anyone heard anything more about this?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic