As for Canonical, it’s published a set of UEFI requirements targeting device manufacturers, and “it’s basically the same set of requirements as Microsoft have, except with an Ubuntu key instead of a Microsoft one,” as Garrett pointed out earlier this week.
“The significant difference between the Ubuntu approach and the Microsoft approach is that there’s no indication that Canonical will be offering any kind of signing service,” Garrett added. “A system carrying only the Ubuntu signing key will conform to these requirements and may be certified by Canonical, but will not boot any OS other than Ubuntu unless the user disables Secure Boot or imports their own key database.”
So, “a certified Ubuntu system may be more locked down than a certified Windows 8 system,” he noted.