Mailing the story:

One of the most disliked features of the early KDE SC 4 releases was the developers' attempt to establish the semantic desktop. The tools to further this goal are Nepomuk and Akonadi. While Nepomuk tries to interconnect meta data from different desktop applications, Akonadi is a service that stores and retrieves data from PIM applications like mail, calendar and contacts. Together, they pave the road to allow users to find data, structured and connected by tags, ratings and comments, covering different file formats. On top of that, Strigi performs the indexing that enables users to find data with simple search terms in KDE's file manager Dolphin.