Boards have arrived! 
I've just put one together with enough components to get it up and running.
Pic 1 shows it in a minimalist config, just one voltage regulator (for the 3v3 rail), and USB/TTL header so it can be powered via USB (USB also provides the power to the 5V rail). The two jumpers configure the power so that the 5V rail is tied to Vin (so the 3v3 regulator gets power), and ties Vcc for the 1284p to the 5V rail (could optionally tie to 3v3 rail, or even Vin if required.)
Pic2 shows it with the CP2102 USB/TTL board plugged into the header, and also a nRF24L01+ radio attached. Serving up web pages nicely via my TCP over nRF24L01+ RFXduino gateway -- more testing to be done, but it's so far so good!
Pic 3 shows him posing beside his little 328p sibling. (I hope you can spot the family resemblance.)
Pic 4 shows him posing beside a Due for size comparison. (Actually, he doesn't really look that big. Maybe I'll end up calling him "Bare Bones Bob", or something. Anyway, he's certainly looking skinny here. 
I'll put up some more pics when he's more "dressed".
