A group of us at Canonical have been working on a document to define the technical requirements for firmware on machines that are to be preinstalled with Ubuntu. Our aim is to make it easier for OEMs and ODMs to configure their firmware to be compatible with Ubuntu.
So, we've recently released the Ubuntu BIOS/UEFI requirements document (PDF, 235k).
If you have any feedback on the document, please let us know, by emailing hwe-docs@lists.canonical.com.