http://ponyconfessions.tumblr.com/disclaimer
(This isn’t porn, and I’m not sure if the blog is still active, but it doesn’t matter.)
Pony Confessions makes its content available under a Creative Commons license, specifically Attribution 3.0 Unported, which allows pretty much any usage as long as credit is given. This makes clear how the moderator wants these confession images to be used, both in the range of usage (pretty much anything) and any restrictions (giving credit).
The disclaimer also states that the moderator does not own the rights to any art used in the confessions. It’s not a stretch to say that none (or almost none) of the artists gave actual permission for their art to be used. Fair use and fair dealing arguments are weak here.
But are the artists okay with this sort of usage? Probably, but maybe not. And this is why I think CC is important in this culture of reusing without permission: It separates those who are genuinely okay with this reuse and those who aren’t, and it makes clear what kinds of usage are acceptable or not. Maybe some of the artists only want their work to be used noncommercially or something like that, or not at all. This is very important in deciding when and how to use work from other people.
For more information about CC and how to use it for your own stuff, check out #Creative Commons on my blog.