Yesterday LinkedIn.com got hacked, and about 6 million passwords were stolen. Those passwords are encrypted, but it seems the hackers are looking for help to decrypt them.
You might, or might not, be one of the poor souls that got their LinkedIn password stolen. Now, the important point is not to change your LinkedIn password (unlike what many sites are wrongfully saying), but to change your password on other sites, where you had been using the same password as on linkedIn. For all you know, the security flaw still hasn’t been fixed on LinkedIn, so changing your password there asap would be perfectly useless.
On the other hands, hackers will definitely try to reuse your old password and email on other websites, which is why it is important that you change those, not necessarily the linkedIn one (but you’d rather change that one once the issue is confirmed to be fixed, though).
linkedIn issued additional information in their blog today, containing more hints on how to protect your passwords on t3h internetz.