Moving to the cloud requires reframing how a business thinks about its data and services. It's quite a leap to get from having everything on premise where you have total control (and responsibility) to having all or some of your key business services and data provided in the cloud. This reframing extends past just services such as mail or collaboration but extends of course into applications and computer power that could be hosted in Azure. While Microsoft servers and operating systems can and do deliver scale to support the biggest farms on the planet, cloud computing and services bring even greater requirements for scale, management, and efficiency.
Who better to collaborate with than Cray on how to provide massive computing power, at entirely new levels of efficiency as service?
See http://news.zdnet.com/2100-9595_22-399926.html