http://krebsonsecurity.com/2014/04/heartbleed-bug-exposes-passwords-web-site-encryption-keys/

http://lifehacker.com/what-the-heartbleed-security-bug-means-for-you-1560801201

Check if any particular site is CURRENTLY exposed:
http://filippo.io/Heartbleed/

Hey everybody, if you reuse passwords at all change them. Except at places that are still exposed to this issue. That wont help you. You are basically at the site's mercy until they update their openSSL.

how urgent is this? im doing lotsa work atm so can someone summarize dis? all this and more affects when im doing this in my schedule.

 
someone worked out how to say to a bunch of secure websites (like specifically ones that are supposed to care the most about security) "hey give me a bunch of data that your computer got in memory right now ok" and what they got back could include usernames, passwords, private messages, encryption keys, all the really juicy stuff that an attacker could use to compromise users & whole sites
 
it looks like attackers have been using this for months before it was disclosed, so, god knows how many passwords and such got scooped in that time
 
it's about as serious as this kind of thing gets