My proof of concept for a battery grip for my Panasonic GH-1 is working.
After a first failed attempt (because red and black wires inside the grip I modified where switched)
I managed to get the Canon 450D -grip working with my GH1 using the default battery-dummy they ship with the camera.
(Optional for the GH2)
I'll take this prototype to CCCamp and start working on the higher level features
like getting the shutter-button to work after the camp.
Then I'll try to write it down as a howto and probably release a video about it too.