Microsoft's Office Insider Program is now available for iPhone and iPad users
Office Insider allows users to provide feedback to Microsoft by detecting and reporting any issues that might be present in early preview builds of the Office package. The program is typically available in two levels – Slow and Fast, the difference between the two being that Office Insider Slow offers early access to fully supported builds of the apps, while Office Insider Fast provides access the earliest preview versions, which are released more frequently, but also might not work properly.
via MSPoweruser
Things that are NOT allowed: