Oliver Hannaford-Day or 'Oli' is the guy responsible for the Coldfire's existance in any form at all. He is designing, building and prototyping the whole thing! and he beat me to buying a promethius expansion on ebay
but I've forgiven him
While very admarable, and definately a worthwhile project, cannot be compared to the Coldfire board, as it does not run AmigaOS of any flavour, but was inspired by, and imitates it.
The Coldfire is an accelerator and expansion system for (potentialy) all Amigas, starting with the A4000 and A3000, as these provide the easiest solutions. Frankly if you've got and A4K or A3K, you'd be mad not to get one... faster than PPC ever will be, PCI slots, PS2 mouse/kbd, USB, AC97 audio.... the list goes on!