Before everyone gets their panties in a twist, wait for Motorola to comment. This is just rumor, after all.
Motorola has admitted that they are locking down the firmware, and gone so far as to say that if you want to mod your Android phone, buy a Nexus One. They have not acknowledged any kind of bricking booby-trap so far as I can find.
That said, I'm most definitely not a Motorola user anyway. I despised their stupid bloody Krazr phone the instant I pulled it out of the box, and when it completely shattered, 2 months later after a 20 inch drop to a wood floor, I didn't improve my opinion of their phones. I don't think this is going to help them much, but I also don't think it's going to hurt them much. As another poster mentioned, it's just not on that many users' radar. Nobody cares except the modding community.
Now, in the interest of Full Disclosure, I expect my shiny new HTC Incredible to be shipped today. This will be my first smartphone (I know, I'm a Luddite), and I don't know what to expect. I don't expect to muck with the boot loader, though I may opt to gain root access after I've studied the pros and cons better.