That's exactly what it does.sounds interesting ... what you meant with 'synch'? maybe you meant that if you did a mod on local automatically this mod will be applied onto the live?
Whenever anyone updates a file, it gets saved with a higher version number and then everyone else can synch and download all the latest files.
I only use if for the local install though, not for the live site as all the coding is done locally and then the final files are uploaded to the live server.