Another "let us code" post here - I don't particularly care how the CAN shield turns out, and it's not going to have any effect on what the CAN API looks like. It's getting to the point that someone is going to fork off and make their own CAN library, but if the efforts happening behind the scenes of this thread are the "officially blessed" efforts, it would be a shame to have conflict in the future.
A GitHub repo with a "This code does not work." line in the README should suffice.