Preview at WWDC likely in June, followed by September launch.
iPhone 5 and Updated iPod Touch to Support Panorama Photo Mode?
[iPod touch] also has that Panoramic photo feature enabled as far as I know. I think the new iPhone does as well.
Strafach has since deleted his Tweet, but says that he deleted it because the information was already known, not because it was inaccurate. iMore's Rene Ritchie says that he heard similar information earlier this year but was unable to confirm it at the time.
Hidden panorama mode in iOS 5
The panorama mode is not entirely new, as it is already hidden in iOS 5 and can be activated on jailbroken devices. Performance was said to be relatively poor at the time of its discovery last year, so it seems that Apple has made significant improvements if it intends to release it as a public feature on its new hardware.
A number of third-party apps such as 360 Panorama and Microsoft's Photosynth already offer similar capabilities, but Apple including packaged within the default camera app on the new iPhone and iPod touch would be a significant boost for panoramic photography.