I've been an eBay seller, and eBay has gone through this type of thing with a huge number of products. Rowling and her publisher are surely far from the first to sue eBay over this sort of thing. I'm not sure who is right or wrong in this case ... okay, I just read the article:
"The injunction presents difficulties for eBay, whether it succeeds or fails in policing its users’ sales. If the company is able to remove all sales of electronic copies of Harry Potter books then other brands will demand similar treatment when their rights are infringed by sellers. If it fails, it will be in contempt of court."
No doubt this is going to cost eBay, which will complain loudly about it, and probably use it to justify yet more seller fee increases.
eBay claims to be "just a venue" but will remove specific auctions if "you" (the publisher or JK or who ever owns the copyright) signs up for their "VERO" program, and then points out each offending auction.
But there's been 'opposite' problem as well. I've read a lot of controversy on eBay's discussion boards, once an individual or company has signed up for VERO they can report auctions arbitrarily, such as (examples I recall) public domain drawings and designs that the company also happens to use. eBay immediately removes auctions on the VERO holder's word, and there's a long and complicated appeals process. For more info, go here:
http://www.tabberone.com/
scroll down and click on Tabberone's Trademark Page and Tabberone's Hall Of Shame.