FileWatch is a program which looks after your files. You can define files it looks after and informs you every time a file is changed (in any way). It's based on file's CTIME value (returned by stat() system call), which changes every time the file's perm. bits, data or owner has been changed. FileWatch is distributed under GNU General Public License.
FileWatch has been made with Perl and requires (as far as I know) perl version 5. It works at least on Linux and should also be working with every Unix. With other platforms, you may have to do some changes to the code.
Download the newest version and then read README.