This is an issue that has been very important to me even before blogs and websites in general. I had what I now regard as an insignificant piece used in a newspaper without my permission a long time ago. I was given no credit and wasn't paid, but the person who submitted it was paid $200.00. That was only the second piece I had ever had published and I couldn't put it in my portfolio.
Today I realize the paper that published it had to be desperate to run something that bad, but it's still a copyright infringement none the less. I see here in this topic and many others I've seen like it across the ether that some people like to make themselves the judge of what deserves credit or permission from the creator or copyright holder. I couldn't disagree more.
No matter how small or insignificant you think it is, if you didn't create it and you don't have absolute assurance that it is in the public domain, then don't publish it without permission. I wrote something about this issue back in 2006. I just began to revamp my enterpriseJM website and it is the first thing I posted:
Copyright Issues for the Blogger or Forum Participant, by Jim McClain | enterpriseJM
It's very nice to find this site. This is my first, but I hope it won't be my last post in your nice forum.
R'gards,
Jim