Ebay has been plagued by a Romanian hacker lately per this article:
http://www.eweek.com/article2/0,1895,2100808,00.asp?kc=EWSTEEMNL030607EOAD
Of interest are the various tactics ebay is using to thwart this criminal which go beyond simple tactics to more complete analysis of hacker activity ...a trend in the industry which has long been needed over an above simple firewall rules and was the reason I started writing this hacker / Internet security / Internet service blog.
More analysis of specific hacker activity by humans, not machines, will help determine traffic and activity patterns to block out attacks better than any firewall rules. It is a constant, on-going effort at mutliple layers from network to firewall to OS to application - it is not a simple one time fix.