From the info I'm reading at various places, this is not just standard cookie blocking like many anti-spyware programs do, and it's not like the Norton blocking that actually stripped the ad or banner. Evidently it will still allow your links and banners to show up but when the buyer clicks the link goes to a page not found error so in addition to not getting a sale it looks like you have bad links. People are saying cloaking does not help but I'm not certain how thoroughly anyone has tested.
DigitalPoint has a discussion going and evidently Ebay rover links are not blocked, only links that use CJ domains, as it appears it's blocking domains at the hosts file level.
(That's what I'm reading but again not sure if all if this is correct or how thorough anyone has tested. Just passing on the info I find.)