'posterun' was searchable for me from Sweden. On my name I only found 3 pieces connected to me, all collabs where I am not the main poster (and a number of pieces with no apparent direct connection with me). Also tested my old deviantart name, with no hits that was mine.
I tested with other usernames that have been mentioned in this thread, to see if I would get similar results as shown in the thread, to make sure the search results where any good. I did get the same results.
So 'posterun' seems to be a place 'non-americans' can use to check if their pieces have been used.
One thing that possibly might have kept my images out of this (if they are, maybe I just didn't find them) could be that I keep the posting size down to 640x480, with the intention that this would generally be to small to use for any commercial level of printing, (or that is what I believe anyway). Just mentioning this as a possible defense strategy.
@Thetageist Searching on my name some of your stuff was shown, and more when searching directly on your username. Just a heads up, so you know.