As part of the forthcoming GNOME 3.18 desktop environment release, the GNOME developers pushed the second milestone towards the 1.6 branch of the Tracker open-source semantic data storage tool for desktop and mobile devices.
Links:
[1] http://www.tuxmachines.org/taxonomy/term/146
[2] http://news.softpedia.com/news/gnome-s-tracker-semantic-data-storage-tool-gets-more-optimizations-and-tweaks-489706.shtml