On the chart I've linked below some Sigma lenses are listed that will work with the GH2. Which version (mount) of the Sigma am I looking for when I'm shopping? Anyone know?

http://panasonic.jp/support/global/cs/dsc/connect/gh2.html

I don't see a link.

ignore post

Four Thirds (as opposed to m43). Still needs an adapter, but some may allow AF n so forth.

example:
Sigma 30mm f/1.4 EX DC HSM Autofocus Lens for Olympus 300107 B&H

Thanks Kevin, I didn't know that 4/3 thirds was an olympus thing, I thought it was a size, not a mount type. I understand now thanks to your post.