Update: This trick is no longer necessary for Windows 8.1 RTM where the bundled Modern File Manager in the SkyDrive app is fully functional.
If you downloaded the build of Windows 8.1 that leaked recently, you may have come across a new hidden Modern File Manager app designed for touch screens. It has no shortcut and is not visible in the application list. The Modern File Manager's files are located in the C:\Windows\FileManager folder.
If you have already installed Windows 8.1, you may want to explore Modern File Manager. Follow this simple tutorial to learn how it can be done.