If they are pictures that you took yourself then other buyers can only use your own pictures if they ask your permission first and you give them your consent. If they don't then report the listing to eBay, stating that the seller in question has used your own photos without your consent. I had a case of this happen to me about three years ago now, and when I reported the listing to eBay the ad was removed from the site within twenty-four hours. If you don't bother to make eBay aware of the matter and make clear to them that you did not give your consent for your own photos to be used on another seller's listing then he'll no doubt get away with it. Get in touch with eBay and make it very clear to them that you did not give the seller permission to use your photos - or anybody else, for that matter - and you should stand a pretty good chance of eBay removing the listing in question.
If you do indeed get lucky and eBay pull the seller's listing when you report the matter to them, make sure that you add the seller's User ID to your Blocked Bidders List, just so that he cannot bid on anything you've got advertised for sale and try to invent some reason to open a case against you as a later date as "revenge" for having reported him to eBay and getting his listing removed from the site.
