Is it possible to use a flash gun other than Panasonic's dedicated unit on the GH1 yet still retain automatic exposure and not damage the camera? Specifically I have a Canon Speedlite 540EZ - can this be placed in the GH1's hot shoe and be used in its TTL exposure mode for bounce work?

tom.

Almost certainly won't do TTL - no control interface with the camera. It'll be fine in manual or non-TTL auto (might need some calibration).

The Nissin 466 is apparently a good fit