I'd also be interested in knowing if the battery is more massive than the iPad 2's. A lot of battery "tech" is in the electrochemistry, and if there isn't a significant difference in mass between the old battery and the new one, then Apple's gone to a more advanced LiIon chemistry.
@samkass — You've got it. That data matrix decodes to S2032J02AAE4S1.
Those aren't QR codes, they're Data Matrix codes. From left to right, they decode to MA1C24VBE2HHT1392, DLN1533001WDL63AE, and 6CBL35515K.
84014789 is very likely the Motorola Mobility part number for either the camera's flexible PCB, or for the camera subassembly.
While it's certainly likely that making the board essentially single-sided kept the overall thickness down, it also speeds manufacturing and improves reliability, thus keeping production costs down.