Any lens with manual aperture ring. The exception is some newer Nikons that lacks a aperture ring but still has a mechanical control lever that the body controls. Those can be used manually on GH1 with a adapter with a ring/plunger.
The major lenses not being able to be manually controlled on GH1 are those with Canon EF mount as those have a purely electronically controlled aperture. As yet nobody has made a m4/3 adapter with such electronics. (It's possible however since Red Rock Micro has added such a EF mount for their 35mm adapter but it requieres reverse engineering of Canon's protocol.)