If you are talking about iMovie version 6, that was designed to handle DV streams from a tape based camcorder via firewire. IMO it remains the best ever version of iMovie - others will argue!
As for other versions of iMovie:
iMovie 11 - cameras supported:
iMovie 9 - cameras supported:
iMovie 8 Camcorders supported:
Digital camera RAW formats supported by OS X Lion:
Digital camera RAW formats supported by OS X Snow Leopard: