This is the only GH1 + 12.5-75mm lens I found on vimeo
We have still to wait a little bit before to get our GH2. To kill the time I searched for some exotic fast zoom lenses that we (and I) might could use on the GH2. There is one particular interesting lens I found on eBay (Click here). The Cosmicar-Canon-Tokina 12.5-75mm f/1.8 C-mount lens! The focal lenght and constant fast aperture is very interesting and but sadly I found only one video taken with the GH1. The Karaoke part is terrible
A few pictures can be seen at Flickr. The japanese website geocities.jp tested the Canon version of the 12.5-75mm lens.
That lens is deifnitely not a professional solution but we have to wait a few months before Panaosnic releases the already announced fast wide and normal zooms!