The GNU/Linux Semantic Storage System (GLS³) is a solution designed to facilitate the management and retrieval of your data. It is a solution that distances you from thinking about Where you store your data to What your data is. With GLS³, you can organize and retrieve your data based on their semantics, based on What they mean to you, and not based on their hierarchical location.
GLS³ is an open source semantic storage solution for GNU/Linux that indexes your data, extracts from it metadata and relevant information, allows you to organize it using queries and tags, an API to allow Developers to integrate searching and organization capabilities in their application, an extensible plugin-based Type System, shared schemas between applications through an API, a pseudo file system for backward compatibility, a web interface, As-You-Type searching and more.
Basically what this brings you is Spotlight-like features to Linux which is nice. There already was another project called Beagle, which is written completely in C# and runs on top of Mono. GLS³ is written in C++ and uses a database (currently Postgres) as the back-end. GLS³ also allows you to tag files, has a virtual file system (see the demos on the site). Interesting. If I’d use Linux I definitely would try it out.