This interests me, Supermicro seems to not offer the motherboard in the Xeon Phi development kit separately, so motherboard availability seem to be the big issue.
The socket LGA 3647 Xeon Phi engineering sample cpu's are popping up on ebay.
A dual socket 3647 motherboard with 512 threads would be fun to play with...... I can dream can't I?
Maybe another socket 3647 supermicro board thats close the the same specs as in the devel kit and flashed with the devel kits motherboards bios would work.......EDIT: Looking at the dev motherboard cpu powerspecs that probably would not be a good idea.