A hacker says he's posted 6.5 million LinkedIn passwords on the Web -- hot on the heels of security researchers' warnings about privacy issues with LinkedIn's iOS app. SourceIf you haven't already started to user stronger passwords. You might want to think about it. However, most people don't really start to worry about such a thing until it happens to them. If you're wanting to be better about making stronger passwords there are all kinds of articles out there but for a quick reference you can check this thread out.
Creating Stronger Passwords