Two things about the lending that I think needs to be emphasized:
1) Publishers can turn this capability off (like the text-to-speech in the Kindle 2 and Kindle DX).
2) You can only lend a book out
once, for 14 days. Once you lend a book out, you cannot lend it again. It's a one time thing.
That first restriction has the potential to make the lending feature all but useless, if publishers decide to take a hard line to it.
Here's a thread from the Barnes & Noble Nook forum.