On July 12th, Yahoo! confirmed the compromise of approximately 450,000 usernames and passwords. If you have any type of Yahoo! account, you should change your password as soon as possible as a precaution. Learn more.
Also, if you are using your Yahoo! password for any other logins (UCInetID, bank, credit card, other social networking sites, etc), you should change your password there as well, using different passwords for unaffiliated sites.
To learn more about password best practices, read our password tips.