Beware: At 12:30 PM (Pacific) today, 06/19/2011, the user database of Mt. Gox (the largest BTC <-> USD exchange) was leaked. Exposed data includes emails/usernames and hashed passwords.
If you use the password you used to register at Mt. Gox on ANY other website, I would highly recommend the prompt changing of said passwords.
Official Updates On Security Breach @ Mt. Gox