Wow! Free cloud storage now 15GB on Google Drive

The 5GB free cloud storage is now enhanced. Google announced the expansion up to 15GB. Users of Google Drive, Google+ and Gmail can now enjoy more freedom of storing their files and folders on the cloud.

But, the announcement came just ahead of Google I/O developers conference to be held in San Francisco. Is there any between this free storage expansion announcement and the I/O event? This is the big question as of now.