I immediately reported the item to eBay for infringing on intellectual copyright (yes, I released it under a Creative Commons Attribution license -- but she hadn't even done that; she was passing it off as her own pattern along with many patterns others had posted to the Commons or elsewhere.) I also sent the user a stern warning to pull the auction. Within a couple of hours the auction for my pattern had been terminated and within 24 hours she had no listings at all. I've had run-ins with eBay in the past but I was happy with how this situation was settled.
Oh, and if you are interested in seeing how Creative Commons can be used well, check out this listing for the same pattern on AllFreeCrafts -- they give proper attribution and even link back to this blog. Well done!