Engadget's photo shoot comparison
Felt this was relevant enough to dpreview that I signed up for an account.
Lumia: 0.3s exposure at ISO 800
iPhone 5: 1/15s exposure at ISO 2500
You really need to download the original photos to get the noise comparison. The difference is immense.
From rough mental calculations (focal length ~ 35mm), the Lumia 920 is getting more than 3 stops of image stabilization. That's quite impressive for a phone, and I don't believe has been done (correct me on this).