there is no WinRT API for this and the WinRT API design does not depend on the current directory.
Use APIs like ApplicationData.LocalFolder
http://msdn.microsoft.com/en-us/library/windows/apps/windows.storage.applicationdata.localfolder.aspx
or uri's like ms-appdata:// and ms-appx::// to address files in your app data and package folder. read more about this here:
http://msdn.microsoft.com/en-us/library/windows/apps/Hh967755.aspx
under the covers the Win32 working directory is set to the package folder, but there is no API to retrieve that.
Chris
