eBay has asked sellers to allow them to use their pictures for eBay's advertising. You can opt out of this but the default is to allow them that use. http://pages.ebay.com/sell/July2009U...ml#advantage\\
Some are concerned that they will be available for 'anyone' to use, but I doubt that is the case. In fact at the bottom of the link provided there is this question and answer.
"What do I do if someone else submits my photo under their user ID?
You should report any activity that you believe infringes on your intellectual property rights immediately through the VeRO program. You can report the problem here."
The comments I see on the discussion boards about this are just supposition on eBay's intent. Nothing is shown to support those thoughts. I know there are some who suspect everything eBay does, and some of this is earned by eBay, but in this case, there is nothing sinister about it.
IMHO they will NOT encourage others to use someone's photo. Just the opposite seems to be the case, since they will give credit and a link to you store in any picture used.