Instead of the Linux Foundation, perhaps the organization could be CAcert? I would think it would be a matter of persuading the OEMs to include the CAcert root keys in the default list. CAcert is a non-profit certificate authority that uses a worldwide web-of-trust model to verify identities. You can sign up as a community member for free, have your identity verified by their assurers at no cost, and then sign all the distros you want.