Well, I'm not entirely sure I understand what "open source hardware" means. "Permission to use the name"? What does that have to do with "hardware" ? If I want to make a couple hundred Arduino-2.1 board to embed in a commercial product (not bearing the name "arduino", but crediting the project in documentation), there are no problems doing that, right? Are you trying to duplicate the hardware, or the entire Arduino "Business" ? I supposed that being FULLY open-source might imply that you could do the latter, but I don't know that I believe that it is in the "spirit" of open source.
The more valid point is that the Arduino team doesn't seem to be following their own "share-alike" provisions with the newer hardware: no CAD files for NG, BT, mini, Diecimila. This also seems "not in the spirit of open source", although it's probably their rights as the original developer.
Finally, there's the whole issue of what makes for "open source" publication of a HW design. CAD files for schematic and PCB in my favorite format are certainly nice, but a printed schematic is certainly more "open" than the average consumer device.