Thanks to your guys' help, I've got my XT907 bootloader unlocked. I've tried installing Beanstalk and Slimroms on my device, but I'm having a problem.
I use the CWM recovery to wipe-data/factory reset then flash the ROM zip and Gapps from external SD. Everything goes as expected as far as the flashing, and then booting into the new system. I go through the Gapps setup normally. However, once I reboot, the screen gets stuck on the bootloader unlocked warning. I've tried flashing a couple of different versions of Beanstalk, the latest being the most current 09/04/13 (and also a slimroms port), but it always fails to get past the warning screen after a reboot.
Inevitably, I go back into CWM and restore backup of the stock system.