For anyone trying to log in for the next little while, the Minecraft Auth servers have been taken offline following an exploit being discovered. They are working on a fix.
Basically, the exploit allowed hackers to login as any premium account that had migrated to a Mojang account. As far as I am aware, this did not affect any of our Guardians.
More details here: http://www.reddit.com/r/Minecraft/comments/wl0zy/psa_exploit_in_minecraft_login_server_hackers_can/