Sundar Pichai said during his talk at the D10 in California that they are going to release offline Google Drive in around five weeks’ time.
I am not sure what he meant by that. Google Drive by design syncs the content between your computer and Google servers. So the files are already stored on your hard drive. Any changes you make offline are synced online as soon as you are connected to the internet.
I hope he means by Offline Google Drive is the ability to edit Google Docs offline which are then synced on Google servers whenever the internet connectivity is restored.
This functionality is already much delayed and is needed for their Google Chrome OS based devices.