Panasonic GH2 has a Micro Four Thirds lens mount and currently there are 125 native lenses available for this mount.
The latest released lenses that are compatible with the GH2 are the Rokinon 7.5mm f3.5 Fisheye, the Samyang 7.5mm F3.5 Fisheye MFT and the OM SYSTEM 9-18mm f4.0-5.6 II.
Panasonic GH2 doesn't have a sensor based image stabilization system but
37 of these lenses already comes with optical image stabilization.
Since Panasonic GH2 has a Four Thirds sensor, it has a focal length multiplier of 2× so you have to multiply lenses original focal length with this multiplier to find the Full Frame equivalent focal length of the lens when mounted on GH2.
You may also also be interested in these:
Panasonic GH2 Lenses with Image Stabilization
Panasonic GH2 Lenses with Weather Sealings