Replying to my own thread with a follow-up...
I've been purchasing quite a few NOOKbooks on my B&N account, but suddenly have a fear that once I register the Nookcolor to my wife, she will no longer have access to all the NOOKbooks I have already purchased in my name. Did I just lock myself into leaving the NOOK registered to me if I want all these books available to her? (That won't be a huge problem, but it would be nicer if it was all in her name, just so she would feel like it's truly hers and she's not just borrowing "mine")
She won't have access to the books purchased under your account if you unregister the nook, then register her under her own B&N account. However, you can download the books you have purchased on your computer (nook for PC), then sideload them onto her nook via USB cord. Or, you can continue to use your account.
Short answer: Yes, you will lose all the books you've downloaded to the NOOKcolor under your email address and password.
Long answer: You still have ownership of those books, and can put them on the NOOKcolor again when you deregister and reregister with her information. To do this,you'll have to sideload them. Go to your account at bn.com and scroll down to the Digital Management menu. There, you'll see a link to go to your library and see all the ebooks you've bought. Next to each book, there's a link to download the books. Download each one to your hard drive (in a place you can find them easily) and plug your NOOKcolor into the computer using the provided USB cable. Find your NOOKcolor drive, I think it's called "media," and open the folder labeled "my documents" or some such. (I haven't actually plugged a NOOKcolor into my computer yet, so I'm not sure what it says exactly) Drag and drop your downloaded ebooks into this folder, and eject your NOOKcolor.
Your books will now be in your library under the "my files" tab. In order to open them the first time, you'll probably have to enter your name and the credit card number they were originally purchased with, but only on the first book, most likely. The device will know then to check the ebook's DRM against what it already has on file.
Unfortunately as it is right now, your books won't show up on the Daily Shelf on the home screen, but you can place them on shelves or wherever else is easy for her to get to. Everything she buys on her own account will show up on the Daily Shelf.
Long story short, you can put the ebooks on the NOOKcolor when you decided to change it over, it just takes a few minutes.
Let us know if you have any questions!
Did you already have the BN account with ebooks for yourself, or did you create it just for this purpose? If you just made it, when it's time to give it to your wife, you can just unregister the nook, change the email on the account to her email, and reregister the nook to that email. All the books you purchased will then be under her name.
However, if you'd had the account already and use it for your own books, that would give them all to her, so the sideloading thats been explained might be the best, if this is the case.