Most filesystems only record when a file was modified (and only the last time it was at that). If you need more information like who did what you're moving into the realm of revision control and will need to go through more than just the "normal" file open/read/write/close operations in order to get changes tracked. You'd need to look into some form of SCM software such as git, mercurial, SVN, bzr (or at a minimum something like RCS, but . . . bleh), but all of those require cooperation from the user making changes and aren't going to just magically remember who's doing what to arbitrary files. If you have non-technical users the simplest option is to provide wrappers and tell the lusers to run make-change-to-foo before they make a change and done-changing-foo afterwards.

I also want to say that I think ClearCase provided a filesystem view to their repository which might behave the way you want (where it remembers who makes what changes slightly more transparently), but it's commercial software with a good sized price tag and has a reputation of being kind of a pain to manage.

Update: added note about CC.