I finally found what I was looking for. It looks pretty damn cool and I believe it s a Fuse based filesystem:
Ext3cow
It allows you to take "snapshots" of your filesystem at specific points in time and then to access older files from the snapshots with a simple set of commands. The snapshot files do not "pollute" the standard file system. There's also a GUI that looks interesting:
The Time Travelling Interface (Should be called TARDIS)
NOTE: It's not yet 100% stable but it's claimed as usable. At least I now know better things are coming. I imagine other filesystems can't be far behind now that the methodology has been created... It's actually pretty ingenious. When you take a snapshot, only one thing happens: The 'epoch' counter in the superblock is updated. Once any of the files on the filesystem are altered after the snapshot point, new blocks are allocated to the modified portions of the file. So... your "old" and "new" files might actually share blocks if the data is still the same with only new modifications being allocated. Pretty cool.