Moving this thread to the all-things-root sub-forum since you can only stop the OTA from nagging you whilst rooted.
Also, check-out binary visions
post re. this from a while back:
where he says:
"If you want to be sure, use Root Explorer or a similar application to navigate to /system/app and rename BlurUpdater.apk to BlurUpdater.bak. Boom, no more update.
If you've modified your system, the update will fail and not change anything anyway... but to be sure, just rename the apk above and it'll remove the update capability entirely.
edit: also, I believe the filename is actually (now) BlurUpdater_VZW.apk
edit: by the way, there's also a BlurUpdater_VZW.odex
file...not sure if that needs renaming, too...?