With the coming new online services (from Office 365 to Azure), Microsoft has announced new support policy for the online services.
As part of this new Support Policy, a new concept called disruptive change has been introduced.
Disruptive change broadly refers to changes that require significant action whether in the form of administrator intervention, substantial changes to the user experience, data migration or required updates to client software.
A key aspect of the new Online Services policy is that Microsoft is committed to providing our customers a minimum of 12 months of prior notification before implementing potentially disruptive changes that may result in a service interruption.
An example of this may be providing notification of a required upgrade to Microsoft Outlook to ensure continued functionality with Microsoft Exchange Hosted Services prior to the change actually occurring with the cloud-based service.
All details are available at http://support.microsoft.com/gp/OSSLpolicy