I forgot where I read it but it seems ORSoC had an agreement with eASIC, however their website only hints at 28nm being released "soon", so I don't think they are the ones.

Looking at the Mars proto, and wondering why they would use the underpowered Altera Cyclone FPGA (150MH/s), I think they might be using the Altera QuintusII/Hardcopy V "process". It's based on the Stratix FPGA, but I don't think it would be a stretch from the Cyclone.

KNCMINER said that they only needed to program the FPGA and the ASIC suppliers would do the rest. That is very much what Altera does and Altera has had a 28nm process since 2010 and is a TSMC partner (they also help TSMC test-drive the various nodes).

So, based on that (however little), I would say they're working with Altera for the ASICs. Now, who will be doing assembly, I don't know...