I found so many different opinions, wether iMovie 09 can handle 60 fps or not ... I tried to figure it out myself.

In the iMovie options you can only choose between 25 fps and 30 fps for importing videos directly from the camera ... but it seems, that is doesn't matter. I uploaded the AVCHD-files directly from my connected Lumix GH1, taking a simple speedy scene in FullHD/30 fps and 720p/60 fps, slowing the whole thing down in iMovie later, to see the difference better.

The 60 fps shots are looking much smoother, which means, that iMovie 09 accepts and keeps the 60 fps after importing the AVCHD files from the camera ( at least from my GH1 ).