My Nikon D800E just arrived and I took some quick test shots. I was processing the files in Lightroom when I decided to try to play around with a severely underexposed image to see if I could "save" it. I was pleasantly surprised.
The darker image is processed with basically default presets in Lightroom 4.1 RC2 (linear curve, Camera Neutral, 2012 profile, no sharpening, no noise reduction). The brighter image is the same file but with some adjustments:
Whites -100 (trying to get some of the text back from the curved metal ruler)
Blacks -30 (to maintain contrast)
Saturation -30 (to undo the tone curve saturation)
Tone curve using target adjustment tool to brighten the top of the white cabinet and darken the lens next to the can.
Sharpening Detail 100 (to kick in deconvolution sharpening)
Luminance NR 75
Profile Corrections enabled for Nikkor AF 24mm 2.8D
Remove Chromatic Aberration (although I didn't see any in the original file, I thought I would play with this)
Pretty sweet results, don't you think? (The crops are 100%).