Motorola confirmed tonight, in a series of tweets, that the Atrix HD will indeed have a locked and signed bootloader. This means that altering the kernel on the Atrix HD will not be possible, limiting the customization possibilities of the phone. In other words, no custom ROMs. The phone, however, should still be rootable.
It’s not the end of the world, though, since Moto also tweeted the following:
“…our goal is still to provide a way to unlock the bootloaders on our devices to those who wish to do so, more details to come.“
So it seems that although the Atrix HD will launch with a locked bootloader, an unlock method may be coming in the hopefully not-too-distant future.