If you use Revolutionary to s-off the bootloader, install CWR (or any other
custom recovery) and root the Thunderbolt, and you are on a Stock ROM, and you don't want to risk problems caused by OTA Updates, you can block them by renaming the file
Code:
/system/etc/security/otacerts.zip
for example naming it someting like otacerts.zip.bak
The file contains the certificate for the digital signatures of the OTAs, if the file is not present the installation of the OTA will not go through cause the OTA update file downloaded on the phone won't be verifiable as authentic by the phone.
So,
don't panic if you see the OTA update being downloaded!
The update file will still be downloaded (it might do more than one attempt too), but it will fail the check and it will not be installed.
If you want to go back and allow OTAs you can just
FLASH THE APPROPRIATE RECOVERY FIRST (that you can find in the
sticky thread in the first page), rename the file back to otacerts.zip and wait for the OTA or check for OTA updates without having to worry about boot problems.
To rename the file is needed a file manager with root capabilities (like Root Explorer or Super Manager) cause the file's permission are rw-r--r-- (or 0644)
Warning:
This little trick applies just to OTA Updates (tested on Stock ROM), it's not meant for and
it won't stop deliberate flashing or updating of ROMs (from recovery mode or clockworkmod for example)