I don't think that ALL implementations of the hardware have to open in order for the project to have "open source hardware." You just need a "core" of implementations that are fully published (and you can't let the unpublished version drift too far from the core.) For instance, I have no problem whatsoever with the fact that third party vendors ("Modern Device Company", "Lady Ada") don't publish full CAD files, but they ARE listed and described as third parties. I'm not sure that it's important that all the "true" arduino hardware be open, but I WOULD like clarification along the lines of "we're going to open the diecimila but we haven't gotten around to it" OR "diecimila is a commercial project based on the arduino reference design and we aren't planning on ever releasing the CAD files for it."