Wow, a 600mm f/4 would be pretty hilarious on a GF2, even more so than a D40 style body.

Instant 1200mm reach!

It is necessary then to get a 10mm lens in order to have at least a resulting 20mm wide, when using a 3/4ths camera body. I like the idea of the 200mm f/4 Nikkor becoming a 400mm f/4 with this EVIL-type camera. I am now eager to see what the Panasonic GF2 may be like (if it ever comes out).

Yes, your lenses will be cropped significantly and your wides will feel quite unimpressive. On the plus side, your 200 practically becomes a wildlife lens :).

Thank you. I am concerned about the focal length a 3/4 format camera when used with regular 35mm lens. I suppose that a Nikkor 20mm f/4 will become 40mm f/4 when mounted with an adaptor on the Panasonic GF1 or similar, and similarly a 200mm f/4 will turn into a 400mm f/4. Is that so? Even my ultra wide 12mm will only turn into a 24mm, so I feel that I shall need a dedicated wide Panasonic lens for true wide angle shots in a 3/4 format body.

With the proper adaptor, yes, but focus and exposure etc will be entirely manual.

I have a 20mm to 200mm range of manual AI and non-AI Nikkor lens, including 24mm, 35mm, 50mm and 105mm. Can I use them in a Panasonic GF1 with a M4/3 to Nikon adapter?