http://opengameart.org/content/a-interesting-note-about-using-cc-20-content-to-make-art-for-oga
Assuming this is correct, and it does indeed seem like it is, we can accept modified CC-BY 2.0 and CC-BY-SA 2.0 works in STK, which will give quite a few more options e.g. for textures. The caveat is that they need to have been modified in some measurable way (and released under 3.0 or a later version) in order to be used, which might be hard for us to track down. But then again, we don't check the origin of every texture or piece of 3D art, because that's what the artists should keep track of and be honest about and include in their license files.
Just thought I'd share it with you all.
