I see that the Atmel ATSHA204A is used to give the device a unique ID. I am curious why this was used instead of using the devices MAC address.
The imp001 cards can be freely swapped between impees (devices with sockets and ATSHA chips). When you move the card, it’ll pick up the right software to operate the host device based on the ID contained in the ATSHA - the software is bound to the device, not the card.
If stuff was bound to the MAC, then unplugging the card and plugging it into something else would still run the same software, which could damage the new host.
If you have two imps and two impees (on the same account) try swapping the cards. Everything will magically continue to work 
That argument only works for the imp001. For later versions which are soldered, perhaps you could have used the MAC address instead?
Later versions do not have an ATSHA. They do use the mac address.
@Hugo, I see your point. As you do know not all situations work for everyone. Was there a way given to the user to opt out of that, and use the mac instead.?
No, it’s part of the system. Not sure why this would be a problem, can you explain your situation?
it is not a problem. you guys remember those “easy” buttons commercials from staples?
http://www.staples.com/Staples-Easy-Button/product_606396
My boss wanted me to use two of these to demonstrate something to sales. Basically press one button and have the other light up and visa-versa. I have the room to stick the IMP in there but not much more. When I say IMP, i mean just the card and not the socket. I could desolder the ATSHA204A and solder it onto the card with 30 awg wire, but it would have been nice to just connect the power to it, and then take one of the GPIO pins for the button and the led and be done.