I know a lot about this device. I preordered one Sep. 30, 2008 and am about to receive it as they are finally shipping them.
There are a few problems with this device for thr purposes of a "100%" open source platform
-Philosophical: It's not 100% open. There are no blueprints available, and proprietary chips and interfaces (SD card reader, etc) inside. Furthermore, while the OS is open source, some drivers (wifi, analog nubs) are not.
-Practical: Even though they're finally in production, you'll probably have to wait a year to get yours if you order now. There are no large scale factories assembling them, it's done by the team behind the product (just a few guys) and any volunteers they can muster.
While an interesting device (and certainly one you can do a lot more with than the Qi) it's not really appropriate for a conversation about available 100% open devices.