EspenB

Yep, its the rumored multi aspect sensor from may. It has the same sensor dimensions as the previous GH2.

Yes, current 20 megapixel sensor is 27 fps at 12 ch readout. The new sensor is 24 channels read out and multi aspect (18.9mm*13mm). Compared to a regular 4/3rds sensor (17.3 x 13 mm) that new sensor seems to have an aspect of 1.45 (vs 1.33 for standard). EDIT: The GH2 sensor is also approx 19 mm wide in video mode. (DPReview says the GH2 sensor is only 18.89mm on the long dimension)

re: B-frames Neither P og B frames is worse than I frames quality wise if the quantization level is identical. All prediction in the encoder is done on the allready compressed frames, so there is no accumulation of the prediction error (which is what is stored for P and B frames).