Still, it is pretty cool technology and I think something that will be integrated with a "real" database near you sometime soon.
But there really isn't a brightline between what's a table, and what's a filesystem, and what's a database. You can put a blob in a database or BigTable, and MongoDB is really close to being a flat file conceptually. You can have a filesystem or database that is content-accessible. You can have a filesystem that is atomic and supports rollbacks and can store relational data like symlinks. A virtual filesystem like LVM can support schema-like volumes on top of it.
At the end of the day it's all just technology that lets me abstract my writes so I can deal with a more simplistic model backed by certain guarantees about behavior. I want to write a program that does XYZ, not write a filesystem/database driver. From there it's all just various tradeoffs.