A common encryption tool used to safeguard transmitted data has been breached.

http://heartbleed.com/

http://www.usatoday.com/story/tech/2014/04/09/heartbleed-five-questions/7501033/

Some websites have implemented the fix, but not all. As I understand it (I'm not a systems programer); If the site is still vulnerable, all changing you passwords will do is allow an eavesdropper to capture your new password. Not vulnerable sites have been fixed and should have the passwords changed, and No SSL sites require no action. Though if you share a password/username with an affected site, it would be prudent to change it.

https://github.com/musalbas/heartbleed-masstest/blob/master/top1000.txt