Evidences of GDrive found on Google Apps
After circulating for a while, rumors about Google’s mysterious online storage and backup service called GDrive were on the verge of fading out, but thanks to fresh new evidence from Tony Ruscoe, who has been impressive at unfolding Google mysteries. Even though GDrive was not publicly released or acknowledged, he managed to disable the service on his Google Apps account. This indicates that Google might be working on GDrive to make it public available.

He discovered the page which disables GDrive on Google Apps, when he was trying to change the query string parameters on various pages. He used the following parameter:
https://www.google.com/a/cpanel/example.com/DisableService?service=www10
The above URL worked for a while, but now Google has disabled "DisableService" page for all services which have not been added to your Google Apps account.
This certainly proves the existence of the service, but doesn’t necessarily mean that GDrive has to be released to public. It was originally thought that GDrive was a service just for Google employees.