Originally, CloudOn launched as an iPad-only app that required a Dropbox account, from where it would get files and would store them. As its legal status cleared, it gradually brought support for Box.net and Google Drive. An Android version came as well.
Currently, you can still download the app for free and use Microsoft Office without paying anything on your mobile devices (although it may be a little slow depending on your connection).
The latest update makes the app universal, also with support for iPhone 5, of course. You can now edit documents, presentations and spreadsheets in your Dropbox, Google Drive, Box.net and even SkyDrive using Word, PowerPoint and Excel through the app.
The iPhone version currently just runs in portrait. However, Lance Whitney from CNET was told by a CloudOn rep that landscape functionality will be available in the next update.
The Android version just added support for Android 4.1 and 7-inch tablet-optimization.
Download CloudOn here.