It isn't much to go on, but a somewhat reputable Twitter account, @evleaks, has leaked what it claims are the first official images of the Nokia Lumia 820 and Lumia 920 with PureView.
Shown below, the phone on the left is the Lumia 920, and the Lumia 820 is on the right:
The Twitter account, which has been accurate with its leaks before (outing devices like the Samsung Jasper and Galaxy Reverb), also posted tweets providing the sizes of the two phones. The @evleaks account claims the Lumia 820 will be a 4.3-inch device, while the Lumia 920 will be slightly larger at 4.5, and will sport PureView, Nokia's imaging technology that was last found on the 41-megapixel 808 PureView.
Unfortunately, the tweets did not provide any more information on the devices' specs beyond the handsets' sizes, so we'll just have to wait and see if these pictures are the real deal and, if so, what is going on underneath the hood.