iFixit is currently tearing down the iPhone 5 and reporting what they are finding. As far as we've already know its a bigger battery and badass chip. Here some updates:
iFixit says because the iPhone 5 opens front-to-back, replacing a crack screen is going to be easier

The iPhone 5 battery is 3.8V - 5.45Wh - 1424mAh compared to the iPhone 4s battery (3.7V - 5.3Wh - 1432mAh) and the Galaxy SIII battery (3.8V - 7.98Wh - 2100mAh)

4G LTE juices come from the Qualcomm MDM9615M

iFixit notes that there was "no way [Apple] could have crammed a 30-pin dock" inside the iPhone 5

Backplate of the iPhone 5 weighs slightly heavier than the 4S

Apple is using a rotational motor with a counterweight for vibration, as opposed to the 4S' "quieter and less annoying" linear oscillating vibrator

The home button now has an "integrated metal support bracket" which should strengthen and lengthen the life of the only front-facing button on the iPhone

Seems like the iPhone 5 should be easier to repair than the 4S—especially in the case of the screen
Check out more over at: [iFixit]