I'm very much into the whole "giving credit" thing...and it's mildly to very irritating when someone posts a desktop shot with rainmeter skins, icons and other items and they don't credit or source any of it. That is why I don't even bother with the lifehacker Flickr group.
It's SO EASY to link to the skin you used! Just paste it and when you post it will say "link". Also, 9 times out of 10 you will be asked for a link to the wallpaper. The other day I saw a reply to that very question. The poster said, 'just do a search for xxxxxxxx'. xxxxxxxx being a vague description of the wallpaper! It was completely rude. I did the search and found the wallpaper quite easily; however, why not include the link?
People work hard on skins and photos and other graphics. If you're going to use them and then post a screenshot, it's a no brainer. GIVE CREDIT.
P.S. This extends to people who "manipulate" images by simply adding words. You should still credit the original artwork. I saw a wallpaper today and it was a well-known (to me) art piece and there were some words added (that's it) and the person made NO mention of the artist whatsoever...it's just a common sense thing to me, I don't know. Maybe I am crazy. I know, the Internet will always be like this and I will always be b!tc|-|ing about it.
stepping off soapbox now