Finally. Office 365 is available for the iPhone, lets you edit any Word, Excel and PowerPoint file - The Next Web

Also consider the free Office Web Apps

"The app has a few catches though. For starters, every users needs an Office 365 subscription, which isn’t exactly cheap. Microsoft Office 2013, installed on a PC, is also a necessity for some of the app’s most pivotal features, such as resumed reading and accessing recent documents.
Office Mobile for Office 365 subscribers is available now in the App Store, but only for users based in the United States right now. It’s compatible with the iPhone 4 and up running iOS 6.1 or later, as well as the fifth generation iPod Touch.
So there you have it. Office on iOS. You asked for it. Microsoft delivered. Eventually."

Finally. Office 365 is available for the iPhone, lets you edit any Word, Excel and PowerPoint file - The Next Web