I've been spending a lot of time working with my students and colleagues on plagiarism and copyright and fair use. The younger they are, the more they agree that it's not fair to "steal" something, but the older they are the more they play the slippery slope game.
Recently I had a disagreement with a friend about a post they'd blogged. It was a link, probably a fairly common one, but one I knew I'd shown them a few months ago. This person posted the link with no acknowledgement. Now, I'm not saying that I was the only source for this link. But it did raise the question of ethics in blogging, something that has been written about far better by others.
I try, to the best of my ability, to give credit for links and ideas both on this blog and in e-mails, papers, etc.. Sometimes "everyone" is linking/saying/thinking the same thing and that's when it becomes difficult. One teacher I had said that if a fact can be found in three or more places, you don't need to cite it. (For example, I don't need to cite Janson when I say that Leonardo da Vinci painted the "Mona Lisa" because that fact is in so many other places.)
Blogs are (for the most part) public forums. Which means that saying things about people should be done carefully. Some people seem to forget this, and then get surprised when it comes back to haunt them. Giving one's opinion is one thing, but libel is another. Some blogs tread that line very carefully, others blow right past it without a second glance.
Basically, I think of blogging as a way to share my ideas with whomever cares to drop by. Because I try to live a morally upright life, giving credit to others for their ideas is the easy thing, the right thing to do. Equally important is not writing posts that might come back to haunt me - in my current job and life, or in a future job and different life. And, dear readers, you have my permission to call me on it when I deviate.