Dataviz, well-known for their Palm OS software, are promising to bring MS Office editing to the iPhone via their new app, DocumentsToGo. The app will be demoed at the Mobile World Congress which runs February 16-19 in Barcelona. The app will also run on Android.
Pricing information has not been released, but the app for Palm OS runs $89.99 in its fullest form, with two lighter version at $49.99 (doesn't support Outlook on that version) and $29.99 (missing a ton of features, like Mac-created doc support). It'd be interesting to see if they stay at that price point or try to go lower - they really have no competition in this arena.