I can't find it specifically but I am sure there's a page somewhere with all these graphics on, probably a forum post.
I can't seem to find it on the wiki (albeit the wiki needs freshening up).
http://freegamedev.net/wiki/There's some general license statement here:
http://freegamedev.net/wiki/FreeGameDevWiki:CopyrightsHere's the only relevant-ish forum thread I could spot. There should/may be more:
viewtopic.php?f=24&t=1021Of course we had that unfortunate forum crash so the details may have been lost in the transition there.