I read a lot of the NoSQL posts that were on HN a few months back, but they didn't have anything but programming details which I couldn't really follow or were

I read a lot of the NoSQL posts that were on HN a few months back, but they didn't have anything but programming details which I couldn't really follow or were not much more than adverts and "wow, isn't this great" stuff. Anyone know of a source, preferably a book, but web will do, that describes the principles of the newer databases as opposed to relations?