Jimbo I think it's a terrible idea to delete images w/o explicit license information because the default assumed license is the GFDL. The uploader may not know that the image needs to be tagged, and we're going to lose many images this way. I've already found one that got deleted, but fortunately the author was still around and reuploaded it:
http://en.wikipedia.org/w/index.php?title=Image:CMOS_NAND.png&action=his...
If the auther is gone, the image is gone, and for no good reason. Additionally, this could mean that images incorrectly tagged with the category [[Category:Images with unknown source]] could be gone in 7 days. Are administrators going to make sure that all images in that category are legitimate before firing away? Expect trolls to start to take advantage of this loophole to cause data loss.
We don't require text to have an explicit license, why should we do this for images? For no explicit license, the implicit GFDL should be imposed unless we find otherwise. If it looks suspicious it can be put to the vote, but I wouldn't make those speedy deletions. We'll use many free images this way.
Dori