It’s almost inevitable. After rolling out the Office Mobile for iPhone app in June, Microsoft has released Office Mobile for Android phones. Available only from the U.S. Google Play store at the moment (according to Microsoft, more countries will be added “over the next several weeks”), Office Mobile allows you to work on your Word, Excel, and PowerPoint documents directly on your Android phones. Document formatting and layout should remain intact after editing (charts, animations, SmartArt Graphics, and shapes are supported), even when you open it up later on your PC or Mac. There are also nifty features like Resume Reading for Word documents, and Slide Navigator for PowerPoint presentations - so hit the source link if you want more details.
Like its iPhone counterpart, you need an Office 365 subscription, such as Office 365 Home Premium. The complete list of qualifying subscription plans can be found here. An Office 365 Home Premium subscription entitles you to install Office Mobile on up to five mobile devices (Android and/or iOS); for Office 365 University, the limit is two mobile devices. If you've more questions, an FAQ can be found here.