In case you missed it, LinkedIn was hacked and password information was taken. The linked article explains what LinkedIn is doing.
What you should do is change your password. I changed mine early this morning when this news first came out, even before LinkedIn had confirmed it to be true. My old password was too short, too simple, and several years old. It was in need of a change even if nothing had happened. Now I have a much better one.
I was inspired to change a few other passwords around the web, too. They were holdovers from past years when password security was much less in need of rigor. Make this a day to beef up your passwords everywhere, too.
Update 6/7/2012. Late last night it was announced that the LinkedIn hacker also leaked passwords from eHarmony. Again, change your password.