Gregory:
I've received three replies back so far, one indicating that her work was indeed "free for any use" but two who complained that stock.xchng isn't clear in their licensing and that their work isn't PD. One of them said his work is cc-by-nc-sa,
That directly contradicts the terms they uploaded them under, which allow for commercial use. To say we have to contact every individual SXC user is like saying we have to contact people uploading their work as CC-BY-SA and make sure that they really "meant it." I disagree with that notion. If people explicitly upload images with "no usage restrictions", then that's what I think we should refer to, unless these people then contact us and complain about the usage.
Erik