I should add: I wouldn't be at all surprised if picscout is running somethings out of israel and some at the US IPs. This is the add on:
http://www.picscout.com/faq/imageexchange-faq.html#IE1I'm guessing, but likely, the business plan is
1) User who wants to find images to buy installs add on.
2) User surface for images. In the process, the visit lots of websites displaying images. When they hit, you see their IP and ua. The picscout add-on sends the URI of all images to picscouts server.
3) The picsout server then hits the images to see what they look like and compares those to images in its database; this leaves the URI's I reported above at the website hosting the image. The server then sends back information to the user's browser. This information is displayed in the browsers sidebar. It includes a link to the web site selling the matching image.
So far-- all hunky dory. But of course, in the meantime, picscout has collected information that-- if they wish-- they can use to discover that a particular site is hosting a copyright violation. So, one might want to block these new IPs. But it's not the same software we were seeing before, and evidently not the same IPS.