The idea of semantic file systems has spread on the Net years (or even decades) ago. There are other projects similar to Tagsistant that you may be interested in. Here is a short list of those one I consider interesting in no particular order.

LabelFS

https://code.google.com/p/labelfs/

Dantalian

https://github.com/darkfeline/dantalian

Tmsu

http://tmsu.org/