As with the original version of Google Drive, Google have now implemented the means to manage versions for non-Google formatted files in the new Google Drive. To access this ability, right-click on a non-Google file in your file list (here a Microsoft Word .docx file), or click on it and select More Actions on the toolbar, and select Manage versions:
This opens a dialog showing a list of the current and older versions of the file, as well as when they were uploaded and by whom.
By clicking on the right hand column icon for each version, you can perform some further actions; delete a version of the file, download a version to your local storage, or permanently save an old version.
Of course, there’s no need to manage versions for files in Google formats.