I don't know it either, very cool though.
This points out PERFECTLY the absurdity of the "Orphan Works" legislation they're pushing in the US right now. Corporations want an abandoned art loophole to give them free art forever. The language for the legislation is mostly borrowed from the copyright laws for print - where there usually IS a clear attribution. Since it's nigh-impossible to figure out where an unsigned piece like this originated, a 'reasonable effort' is never going to be enough to locate a possible copyright holder. The proposed recourse for the infringed artist is useless for those of us without bags of money to spend on legal fees (if you find out, you can sue only for what you would have been paid).
Info for the interested:
http://asmp.org/news/spec2006/orphan_faxcall.php