Alright, I'm going to start off with saying that what this does is turn off FOTA for you by modifying data for devicemanager. How do you do it?
Well, let's begin.
12/22/11: New tweaks, FOTA checkin timer = 0 (no checks anymore), Build key difference, FOTA mode = disabled and a few other FOTA tweaks.
First: Download the files unzip them, and put all 3 into the TitaniumBackup folder on your sdcard (you need to download Titanium backup from market for this just FYI).
Then start titanium backup, grant root if you havent already and restore "DeviceManagerService 2.3.4" and then poof! You have now blocked OTA's. I'll actually try and make this happen in my script so new people can do it but you can tell if it worked by going into settings>about my nook>Version Number:9.9.9
Will this stop me from buying anything from B&N?
NO! You will keep everything and the ability to buy. This does nothing to the services aside from makes a few minor SQL tweaks that affect the devices ability to OTA.
Can this break my device?
No! This process actually holds no risk. It should always work no matter what and since we caught it early on, we can prevent further updates that can fix this.
Are you awesome Indirect?
Yes, yes I am. Now enjoy all the crap I released for you guys