It was announced months ago that they were going to do this. I'm surprised it took them this long to finally start working on it.
Cingular was a conglomeration of multiple wireless companies owned by SBC and Bell South. They merged them all into one and split the new company 55% to SBC and 45% to Bell South. Most of the assets were TDMA based and a few markets were GSM/GPRS/EDGE. It took them a number of years to transition to all GSM. When they acquired at&t wireless, they also gained their first UMTS holdings with even a phone or two. However, from what I read somewhere, they shut the 3G off (don't hold me to that, because I don't remember where I read it). I will re-read the Cingular history and post more later.