So I'm in the middle of web-based filesystem abstraction layer development. 
Just like file browser, except it has some extra features like freaky permissions etc. 
I would like users to be notified somehow about directory changes. 
So, i.e. when someone uploads a new file via FTP, certain users should get a proper message. It is not required for the message to be extra detailed, I don't really need to show the exact resource changed. The parent directory name should be enough.
What approach would you recommend?
A simple approach would be to monitor/check the last modification date of the working directory (using os.stat() for example). 
Whenever a file in a directory is modified, the working directory's (the directory the file is in) last modification date changes as well.
At least this works on the filesystems I am working on (ufs, ext3). I'm not sure if all filesystems do it this way.
Directory checksum with python?