With the latest Android 2.3 Gingerbread ROM leak came the news that the Motorola Atrix 4G, to get the refresh soon in July, will also get its bootloader unlocked straight from the manufacturer. It looks like you don’t have to wait for the update to be rolled out in order to have your bootloader unlocked.
The good folks over at XDA Developers have managed to find a way to unlock the bootloader on the Atrix 4G running Android 2.2 Froyo. Of course it’s a bit more complicated that what the official version will be as you have to flash a special SBF and then run commands from the fastboot menu of the phone. There are risks involved of course like with any major flash, hack or tweak you apply but if you acknowledge that and still decide to move on, follow the source links below for instructions.