When blogging, I try to be aware of certain copyright issues. Whether it's a photo or text, I always strive to credit the source.
However, as pointed out on Concurring Opinions [What If Copyright Law Were Strongly Enforced in the Blogosphere?
], "Suppose the mainstream media, fed up with the buzz bloggers keep getting and with bloggers criticizing their stories, decided to exact revenge. They initiate a vigorous copyright enforcement strategy, launching a barrage of lawsuits against bloggers as the Recording Industry Association of America (RIAA) has done to music file sharers. What would happen?"
It's an interesting supposition, but one any blogger should consider.
Then, there is always the issue of blog post piracy