The Wall Street Journal is reporting today [subscription] that AT&T is expected to announce a partnership with Sprint to offer wireless service to AT&T customers. The announcement should come this week, but won't take effect for a while:
The new cellular service could begin as early as this fall if Cingular Wireless closes its $41 billion purchase of AT&T Wireless Services Inc., potentially becoming the nation's largest cellphone operator.
Even more confusing, due to a previous agreement AT&T will be able to market the service under the AT&T Wireless brand name.
The journal goes onto say that in semi-related news, Cingular Wireless and T-Mobile USA are, "In discussions to end a network-sharing arrangement, resulting in a payment to Cingular of roughly $2.5 billion, according to people familiar with the matter." This is due to Cingular not needing network sharing once it has control of the AT&T Wireless network.
Update: The deal was announced hours after this story was published.