eBay has modified sellers' ability to block bidders. Buyer requirements allow sellers to block buyers from bidding on or purchasing their items based on criteria such as their country of registration, their buying history on eBay, and whether or not they have a PayPal account. Sellers use the feature to help minimize the impact of high-risk buyers, and eBay allows sellers to block 1,000 User IDs by adding them to their blocked-bidder list.

Starting this week, eBay said sellers will be able to review a new Buyer Requirements Activity Log. The log will show who has been blocked in the previous 60 days by Buyer Requirements preferences. Sellers can also exempt certain individuals from their bidding restrictions by adding them to an exemption list.

http://www2.ebay.com/aw/core/200602071036402.html

http://pages.ebay.com/help/sell/buyer-requirements.html