The key? This tidbit buried deep in the Yahoo Answers beta:
- Call customer care at 408-349-1572 open 6am - 6pm PST and say that your account got compromised. There is also an e-mail address: email@example.com.
Moment of Screaming Irony: I was only able to find this info by searching for "compromised yahoo account"... in Google.
Doesn't that just about say it all?
(on a separate note, OOO... the ability to turn off auto-formatting of HTML! Woo!)