"Somewhere I used to work the wired network was set up to block anything with a non-whitelisted MAC address"
One my clients, a university, used to do that too. But they had the switches set to block the port if an unauthorised MAC was detected. The PC team had to request the networks team to unblock the port, which always seemed to take a day or two. It was a pain when a motherboard (or a network card in some other kit) had to be replaced with it's change in MAC address and the person doing the repair didn't know about it. I heard they changed that policy one year after some students, on "discovering" this, DOSed an entire floor of CompSci by plugging their laptops into every port available.
Other sites weren't so restrictive and MAC changes just had to be notified by phone with PC name and new MAC address and it was usually up and running in minutes.