It's a little involved but better than re-typing the passages you'd like to share yourself:
1. with the passage you'd like to copy showing in Nook for PC, while holding down ALT key press the PtrScn key. This will add the graphic for the entire screen into your copy buffer.
2. open the Paint app that's present on all windows machines
3. in paint while holding down the Ctrl key press the "V" key to paste the screen image into paint
4. Using Paint's crop and erase functions whittle the screen image down to the smallest image containing only the desired passage. Save the resulting image.
5. Go to this website or another providing similar function:
http://www.onlineocr.net/
6. use that site to convert the image to text or word then edit the result text file as needed.
Naturally you have to do this multiple times when a passage is split across one or more pages. Still it's easier than typing it all in yourself. There are also opportunities for partially automating this process by some motivated tech-savvy person.
B&N or publishers need not fear because it would be impractical to copy an entire book this way. I have been frustrated in the past when passages I'd like to share are slightly longer than the unnelievably small amount of text that B&N will allow you to post or email.