Nelson's confirmed that unMicrosoft 360 storage devices won't work with the machine when its November software update goes live.
"One of the changes is that unauthorized Memory Units will no longer work with the Xbox 360," said the exec.
"If you’ve moved your profile or saved games onto one to 'back it up,' you’d better move it back onto an authorized Xbox 360 storage device prior to taking the update.
"If you continue to use an unauthorized Memory Unit after the update, you will not be able to access your stored profile or saved games."
For a look at some of the update's features in action, take a look at this.