There are tons of new Panasonic GH2 user reviews and I made a quick summary of the most interesting tests:
GH2 vs GF1 ISO Test at same Shutter Speed and Aperture (bmupix).
GH2 Video Features Demonstration (DVXuser forum).
GH2 Extra-Tele Slo-Mo Surfing (Vimeo).
The Path to Micro Four Thirds (Pitofknowledge).
GH1/2 Skew Comparison Test (Vimeo).
Very long user review at Amazon.