Microsoft is reportedly developing a version of Windows Server for ARM-based servers. The big question is what Microsoft would get out of such a move. According to Bloomberg, Microsoft is exploring ARM servers.
ARM servers, which have a tiny sliver of the server market today, have generated buzz due to their energy efficiency in hyperscale data centers. ARM could also theoretically give Intel a run in server chips. Meanwhile, Intel is trying to break ARM's lock on mobile.
Hewlett-Packard has popularized ARM-servers with its Moonshot effort. In addition, ARM processor vendors are powering a bevy of specialized servers.