I tried the Leaf Aptus 54S at the PhotoExpo attached to a H1, and it was fast. The specs says 0.8sec. per shoot or 75fpm. When I tried it, it was definitively around 60-65 frames a min., and it's a 22Mp full-frame.
It uses firewire 800 or Sandisk's new cards and reader.
The new Phase One P25+ is advertised to be 40 frames per min. (real world probably around 35fpm.) and uses firewire 400. Quit a gap.
We are expecting our 54S in January, and if I sound a little excited, it's because I am.