I would also like to see a new classic Amiga motherboard. Probably the cost is too prohibitive as has been said, but what do you guys think about this approach. In order to take advantage of existing, cheap, readily available parts wherever possible, make a motherboard (AT/ATX formfactor?) with PCI slots, SIMM or DIMM slots, headers for serial/parallel/disks/video, sockets for CPU/ROM/custom chips.
Then the user can go to his or her computer scrap pile and grab a 680x0 or PPC CPU from an obsolete Mac, spare OCS/ECS and CIA chips, PCI SVGA/ethernet cards, and standard RAM/case/PSU.
If some kind of OS4-capable PPC board will come along soon and offer an acceptable price/performance, that would be nice too.