It's become a commonplace story for bloggers to express moral outrage. A blogger comes up with some bit or some scoop; somebody from the "mainstream media" uses said bit or said scoop without crediting the blogger; bloggers express outrage. Recently, The Big Lead suspects a scoop of its own was used without credit by PTI. A few months ago, YAY Sports was upset with Scoop Jackson for stealing a bit. Last year Colin Cowherd used some material from the M Zone. And people were (rightly) angry about these things.
That's fair. Anytime you are borrowing somebody else's ideas, you should identify the source of those ideas. I teach English; I emphasize again and again that you must cite any borrowed material. Bloggers have the right to moral outrage when their material is used without credit, or even when their comrades in blogging have their material used without credit.
But, Mr. High Horse Blogger, you probably have your own issues to worry about.
You're probably flouting copyright law every time you blog.
Because photos are copyrighted material. Just because it is easy to copy and paste pictures with a computer doesn't make it legal. Just because everybody else is doing it does not make it right.
If you are going to use a photo that you lifted from somewhere around the web, at the very least you need to credit the source of the photo. But I'm not even sure that's legal. Probably, you need to get permission to use the photo. There are a few exceptions. "Fair use" generally means you can copy borrowed material "for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research" without infringing on copyright, according to Title 17 of the U.S. Code. But I doubt using a recent photograph to supplement your blog entry, without comment on said picture, fulfills the standards of Fair Use.
There are also a lot of images out there that are now in "public domain." These images could be in the public domain for any number of reasons (usually they're just old), but once they're in the public domain, they're yours to use.
But I'm no copyright lawyer (maybe someday). There are other sources you can use to learn more:
The University of Maryland University College provides data on fair use and copyright.
Here's information from the U.S. Copyright Office (probably a reliable source on copyright) on Fair Use.
The U.S. Copyright Office also gives you the actual legislation.
Bitlaw deals directly with using images online.
So I join you in your moral outrage; members of the mainstream media should not use material from blogs without identifying their sources (though it's legitimate to ask at what point a story is just "out there" as "common knowledge" and no longer requires citation). But when you decide to get morally outraged, make sure you're not participating in a similar transgression.