One other thing to note in this discussion is that the Arduino.cc site is only advertising "official" Arduino products... there's no mention of the Barebones Arduino or the Runtime Arduino...
If the hardware were really open, wouldn't one also advertise those products as interesting and valid variants of the project? Protecting your market share in that way by only advertising your own products, to the exclusion of other products produced by the community, seems contradictory to the goals of open-source projects. Of course there isn't much history to go on here, but it doesn't seem right.
The more I think about this, it seems that the Arduino project is really an open-source software and information project wrapped around a closed hardware product.
D