While users of Office 365 for business and education have had to use the service-specific portal to sign in, they will soon be able to kick off the authentication process via Outlook.com instead.
Sign-in page RSS
Microsoft has officially announced the public preview of its new login experience for Azure AD and Microsoft Account. It brings a new UI and aims at unifying the sign-in experience across services.
Attempt to sign into any of your Google accounts, and you'll see a little notice at the bottom, saying a "new look is coming soon". It's expected to show up to users "in the next few weeks".