A team of hacks calling themselves d3dd3 have revealed and posted over 400,000 Yahoo email passwords. At this time the members are unknown and capable of repeating this attack on other personal services such as Hotmail or Gmail. Yahoo has made and apology but has yet to comment on the situation. You can go to Sucuri to find out if your email accounts password was revealed.
If you use any public email services especially yahoo now would be a great time to change any passwords that you have had for a while or that you do not change on a regular basis. Also if you are concerned about keeping your information confidential you can look into multi-factor authentication. This combines your password with another method of authentication. Google for example has a tool you can install on your phone called Google authenticator. With this enabled when you log on to a non-trusted computer you must enter your password and then open Google authenticator on your phone and input the number it gives you. This number changes every 30 seconds to prevent password capture.