An ad on the S60 5th edition app for Accu-Weather shows a model named the Nokia Saga. The previously unknown device looks like a cross between the 5800 XpressMusic and the E75. As Symbian-Guru points out, Nokia usually doesn't give names to its phones, leaving it up to the carriers to do so. This means the Saga could be a branded N97 or mini N97. Or, considering the ad mentions Nokia Messaging, this could be the first touchscreen E series device. Whatever the device is, it is unclear if Nokia had wanted the handset to be outed at this time.
A late update on Symbian-Guru says that according to David Fields of the Nokia Messaging team, the phone is merely a N97 mini. That doesn't take away the mystery over the "Saga" name unless it is a branded version for a unknown carrier!