Neat! I was meaning to write a FUSE filesystem for my personal use that exactly accomplished this with EXIF data. I don't feel as motivated to do that now, will give elodie a spin instead.
I think this GitHub issue [0] refers to what you're saying. I've sort of accomplished it with scheduled tasks but something a bit more native is a great idea.
I wrote about it a bit here [1] under "the file system as a real time reflection of its contents"
