Fellow WASC officer Ryan Barnett has published findings pertaining to a distributed brute force attack against Yahoo's login pages as part of his findings for the WASC Distributed Open Proxy Honeypot Project . For those not aware of this project, Ryan leads an initiative where people run open relay proxies and centrally upload the logs for analysis to see how people abuse open proxies. Rather than pasting a brief summary as I usually do I advise checking out the link below.

Yahoo Brute Force Findings: http://tacticalwebappsec.blogspot.com/2009/09/distributed-brute-force-attacks-against.html