To whom it may concern,
You may not know it, but there is a rapidly growing movement of people trying to make an open-source BIOS. In fact, they've already succeed for many motherboards. You can get more information at coreboot.org.
I know that if you open source your BIOS, then other companies will copy you, and for this reason I do not ask that you do that. If you open-sourced the BIOS only once it has reached end of life, you would not be giving up valuable intellectual property, and you would increase your reputation within the open-source community.
Yours sincerely,
orthogonal