Microsoft Office 15 suite in Windows 8 will include a "touch mode" to enlarge the ribbon interface and other UI elements for the tablet users. The mode will include an animation of a number of Office features, and bigger icons and spacing in the ribbon.
The new touch mode does not work fully in the latest Technical Preview version. There is no word on the rumored radial menus in the latest technical preview builds, although this new style menu is designed for the OneNote Metro style application and not the desktop versions of Office 15.
Office 15 apps are currently in Technical Preview with a beta scheduled for summer, and some will be packaged as part of Windows on ARM.
Source: ZDNet's Mary Jo Foley