Take this with a grain of salt, but according to P3Droid, he alluded to the fact that the Nexus may some how keep track whether or not it's been unlocked. I don't know if it's true or even possible...
Not that it means anything but I've heard grumblings about the boot loader as well. I can tell you that it is/was a big security concern of Verizon's.
I don't know anything beyond that so nothing will surprise me once its released. I am very curious to see the outcome though. I don't expect it to be locked but I wouldn't be shocked to be perfectly honest.
Sent from Droid RAZR