Diwa labs tested a GH2 pre-production unit: Panasonic Lumix DMC-GH2 - Lab results - diwa-labs.com

You can compare the results with the GH1:
Panasonic Lumix DMC-GH1 - Lab results - diwa-labs.com

Pleas ekeep in mind that this results are based on a GH2 with firmware version 0.2!