A new activity stream in Drive shows you what’s changed

Over the next few days, you’ll notice a new activity stream in Drive. When you open Drive, click the “Details and activity” button (ⓘ) on the top right corner and the activity stream will appear, showing you who has taken action on files and folders in My Drive. You’ll see a rundown of what your team has been doing, such as editing and commenting on notes, adding a new spreadsheet, renaming a presentation, etc. If you select a specific file or folder, the stream will change to show you specific information about that item.

Release track:
Rapid release

Editions included: 
Google Apps for Business, Education, and Government

For more information:
https://support.google.com/drive/answer/3323935
http://googledrive.blogspot.com/2014/01/a-new-activity-stream-in-drive-shows.html

Reference by : http://www.google.com/