It is not a feature announced by either Microsoft or Nokia during WP8.1 announcement. So, I assume this feature didn't make it to WP8.1 or any of the upcoming Nokia phones like 630/635/930.
I don't see why it is useful for enterprise use. Most enterprise ITs want to disable SD card and any external USB storage usage or at least make encryption on them mandatory. None of the Google Nexus devices have official USB OTG support without 3rd party hacks or software either.
