According to Gerd Knops:
Linux has Fuse, which makes it quite easy to write file systems in userspace code. I wish there were something similar for OS X. That would make it quite easy to implement file systems based on sftp etc.,
This is [again] where a VCS (or even better a distributed VCS) shines. You work locally and commit/clone/push/whatever your modifications to your production/pre-test/test machine.
You get the same advantages as rsync/transmit/fugu but you also have history, rollback and all the good stuff coming from VCSes...
or even file systems that hook directly into svn etc.
Transparent VCS are not IMHO a good idea, you lose many of the advantages running one if you don't know it...