Developed as part of KDE4 was Nepomuk to handle meta data of all kinds on the desktop in a generic fashion regardless of file type as a step towards a semantic desktop. While Nepomuk continues to advance, the KDE developers are now collaborating with GNOME developers to bring Zeitgeist
to the KDE desktop too. Zeitgeist is one of the GNOME 3.0
projects and is basically a desktop engine for logging and tagging all sorts of desktop activity from document openings, the web-sites you visit, emails and notes you create, etc. This information is stored on your system in a central database so that via other GNOME applications you can access this data or perform queries to help you in different ways.
With Nepomuk and Zeitgeist complementing each other nicely, the KDE developers are looking to leverage both projects so that the KDE desktop can then effectively provide answers for commands like "Give me most listened to songs by Michael Jackson." Alternatively, "give me all recent contacts tagged with work that I contacted from home."
It will take some months before you will see Zeitgeist appear in KDE, but all of the details surrounding their plans and the collaboration between developers can be found in this blog post
. Meanwhile, on the GNOME side, Zeitgeist will be properly making its debut with GNOME 3.0 in March. One of the ways the engine is used within this release is via the GNOME Activity Journal