Major Nelson has said that "unauthorised" Memory Units will no longer work with Xbox 360 once the next system update, currently undergoing testing, is applied.
Writing on his blog, the Major - Microsoft's Larry Hryb - advised 360 owners that they should buy an authorised storage device - either an official Memory Unit or hard disk - to store their profile or saved games instead.
"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," he explained.
This has not gone down fantastically well with the Xbox 360 faithful, who are currently arguing about it on the blog to the tune of 400 comments.
Although some point out that this is presumably an attempt to rein in hackers, others suspect it's more to do with squeezing third parties out of the lucrative accessories market.
Other others, meanwhile, argue that you could understand Microsoft protecting its bottom line, were the platform holder not charging extortionate fees for its own Memory Units and hard disks, and were it to provide units with as much storage as its unofficial - sorry, "unauthorised" - competitors.
Microsoft hasn't clarified the statement on Major Nelson's blog, but the man himself did pop up on the comments thread to say that he had read everyone's posts and had "echoed some of the concerns posted here w/ the accessories team".
The system update also adds Twitter, Facebook and Last.fm support, and we also recently learned that there's a "News and More" tab on the Inside Xbox channel. Hot.