Originally Posted by CrashTestDroid
It's not locked in the anti-user AT&T/Samsung/LG/HTC fashion if that's what you mean. Installing a new rom won't void your warranty or leave a visible footprint during bootup. You can unlock the OPO and install custom roms or leave it stock. Stock CM11S is pretty good.
You forgot about verizon, the pioneers of anti-user policies :P.
Anyway yes the bootloader is locked by default, and can be unlocked very easily. Best part is if you unlock it there is nothing visible during bootup or regular use that screams unlocked like with the nexus (the unlocked icon).