Nice cam the Panasonic G1!
Because of the 20mm flange-to-sensor distance it can be used with ANY lens from C-mount size upwards.
I am waiting for adapters to arrive before testing existing Canon FD, Leitz, Schneider, Rodenstock, Taylor Hobson and specialised machine-vision lenses.
(with a C-mount adapter, the lens protrudes 2.5mm into the body to give a 17.5mm distance)
Just wish it had live HDMI ....