The last time I used some Intel hardware, it's documentation came in a series of databooks that were color-coded as to their level of secrecy. Yellow-covered books you could get by agreeing never to let them out of your office, and to destroy them when you were done. Orange-covered books were supposed to be kept under lock and key, and returned to Intel when you were done. Red-covered books (I don't think I got to see a red covered book) could only be looked at if you were being supervised by an Intel employee. (Something like this, anyway. Fierce!) BIOS-writers would need access to all of those. I was writing bare-metal code on a production motherboard that had already be set up by a third-party BIOS, so I got away with mostly yellow books.
If this "open source" board of theirs can be programmed from the ground up without having to to go to such non-disclosure extemes, then it's a pretty major improvement, IMO!