The facebook app uses the owner name (which cannot be changed in spite of changing it at bn.com) instead of the facebook name when posting. This means that it post something to Owner Smith's facebook account saying OldOwner Smith enjoyed the book.
Since many of us had accounts that predated the Nook Color and its social features, we could not have predicted it using this account name for posts. Fixing your name (on the same account) on bn.com does no good and keeps a lot of people from using the features (and helping bn.com sell more nookbooks). There is no reason that the app could not use the facebook or twitter name instead of the owner name that may be dead wrong.
If you aren't the original owner and you want that information fixed you need to reset and reregister the Nook not just change the account name at B&N.