Rumors so far:
-4" screen (so I guess Apple fans will now say that 4" is the perfect size, not those lame 3.5" screens!)
-1139x640 res, 16:9 aspect ratio, so the res is longer but dpi remains the same. Still 640px wide
-LTE if you care
-No NFC
-Most likely the same CPU and GPU (so dual core ARM9 + SGX GPU) but CPU should get a 32nm die shrink
-3.8v battery, higher capacity + cpu die shrink means battery life should be pretty impressive
-new dock connector, so get ready for some $20 adapters