I see noone on here is a believer in the holy public domain.
My first foray into ebooks was from borrowing a spare ereader from a roommate who was a pirate. He gave me a chunk of his collection, and I think I still have it somewhere.
I no longer read pirated books, for reasons already discussed on this thread. However, if I bought a book from Amazon, there is no way I would leave the DRM on it. Besides the fact that I use a nook, Amazon has a history of reclaiming books they have already sold. Yes, it happens rarely, but I have read their TOS, and even if that was a few years ago, it makes me feel like they are evil.
I will remove the DRM from a free book if I want to give it to someone, I can't understand why they DRM them anyway.
I have never lent an ebook to anyone, although I have traded ereaders for a week, or even an ereader for a book for a while. I do not see anything wrong with that.
I personally dislike the fact that I cannot lend ebooks easily like pbooks morally. I actually read this thread hoping someone would have a solution to that, but noone did.