The "bring your own device" (BYOD) trend is sweeping enterprises, and end users are clamoring for the ability to use products like Office and SharePoint from their mobile device of choice, Creese said.

"If Microsoft pooh-poohs that reality and says it'll only put Office on Windows 8 tablets, that means they just don't get it," Creese said.

How Microsoft optimizes its applications for the various mobile devices is a tall order that will involve re-thinking their purpose and use in smartphones, touch-only tablets and hybrid devices that have both touch screens and mice/keyboards.

It might mean offering some applications via mobile browsers that support HTML5, while delivering others as platform-specific apps.

"The form factor influences what you can and expect to do with the applications," said Philipp Karcher, a Forrester Research analyst.