I think that the Kindle and the Nook will have little impact on libraries until they are lower in price. The Kindle and the Nook are really performing the same function as ebooks. There is a website http://worldlibrary.net/ where for a monthly subscription, you have access to hundreds of thousands of titles that can be downloaded to a Kindle (just as ebooks can be downloaded to a computer). The minimal fee may have a draw for those who already own a Kindle, but the price of the device itself will deter many. Right now, they are just portable book stores that not everyone is willing or able to buy. Until these devices are adopted by the majority of the populace, they won't have an impact on libraries.
This past Christmas I got to see a Kindle up close and personal. A relative of mine had gotten one as a present. I had been pretty opposed to them before, I like holding a physical book and being able to flip through the pages (which both can be done with a Kindle, but not as quickly). It was pretty neat, but I don't think I'll be getting one any time soon.
