It's not easy, and it's surely not pretty, but a handful of developers are making headway into breaking the Nook Tablet out of it's B&N jail and making it a full fledged Android tablet. On paper, it's one of the best Android tablets for the price, but Barnes and Noble have locked the Nook Tablet up pretty tightly. Because of the penchant for Android users to want instant results, the whole thing has turned into a drama-fueled mess of epic proportions, but in spite of all that we've seen a method discovered to bypass the bootloader security, a custom build of ClockworkMod recovery, and a booting port of CyanogenMod 9.
It's not ready for prime-time, and the discussion is pretty technical. It involves things like bootstrap loaders hijacking the standard method to boot the darn thing. The good news is that the fellows working on it seem to have all their ducks in a row, and with a little luck and a lot of patience we just may see this one unlocked and given the same treatment it's older brother the Nook Color received. Visit the source links, and be sure to thank nemith and company for all their hard work.