Reports have come in that LinkedIn has been hacked, and that almost six and half million user passwords have been published on a Russian site. They’re stored as unsalted hashes and, especially if you have a relatively weak password, may be easily cracked with rainbow tables. If you use LinkedIn for making professional connections, as so many folks in the IT field do, be sure to take the time to change your password as soon as possible.
In addition, if you do what we all know we shouldn’t (but sometimes do) and use the same password for another site(s), be sure to change the passwords on those sites, too. It’s a royal pain, because it can mean changing your password in all the client programs (email clients, social networking apps, etc.) that have used that password, but it’s better to be safe than sorry.
Read more here:
http://mashable.com/2012/06/06/6-5-million-linkedin-passwords/