All I can assume is that someone convinced Amazon that they were S.K.S. Perry, and submitted my book for sale. I have no idea how hard that is to do, or what steps Amazon uses to verify that you in fact have the right to sell whatever book on their site, but obviously in this case their process has failed. Amazon has a copyrite email addy to address this very kind of thing, and I've contacted them to let them know, but as yet I've heard nothing back.
I had considered putting Darkside up myself for .99¢ (apparently whoever posted it thinks its worth more than I do!) but now I guess I'll have to wait for this to be resolved.
After that, I think I'll try and sell the sequel before someone else beats me to it.