I, and others have had not luck logging into websites using Microsoft Passport Authentication. However, MSN Messenger logins work which use the Passport Authentication.
Known sites:
Hotmail.com
direct.msn.com (when logging in)
BetaPlace
Connect
I am sure there are more.
I am not sure when the problem arised, but I would say around 10a-11a EST is when I first tried to login to MSNDirect website to add traffic sensors to the traffic channel.