PSA: Blizzard NA Bnet change your passwords

http://us.blizzard.com/en-us/securityupdate.html

See link for full details, short version, Blizzard has found determined some information was hacked, and are suggesting NA accounts to change passwords.

Secret Questions may have been compromised as well.


For more on good passwords see Steve Gibson's Haystacks & Needles (Understanding Passwords)

I would also strongly suggest Two Factor Authentication.