For the Galaxy Note 2, Samsung used the model number GT-N7100 for the generic international version of the device and GT-N7105 for the international LTE version. If Samsung are following the same numbering scheme then the photo could indeed be from the LTE version of the Note 3.
However, a little caution is needed. It is very possible to fake EXIF data and the photo only has a resolution of 1024 x 576 which is VERY low. The image is also very blurred.
But if it is genuine then it looks like Samsung have a few prototype Note 3 devices out in the field for beta testing! It is anticipated Samsung will unveil the Galaxy Note 3 at IFA 2013 which was also the event chosen by Samsung to launch the original Galaxy Note and the Galaxy Note 2.
As for specs, the current rumors suggest at least a 5.7 inch display and couple of different CPUs. Like the Galaxy S4, which has two processor variants, the Note 3 is expected to come in Exynos Octa and Qualcomm Snapdragon flavors.