Xesam is the project to create a unified API for desktop search and meta data services. The development currently focuses on finding the right way to represent the shared ontologies.
Xesam, which was announced as Wasabi in February this year and was renamed to Xesam in March aims at providing general desktop search APIs (think of D-Bus here) for desktop search and meta data services. The advantage is that you could write a search GUI without caring which search machine is actually working in the background. This would make it easier to switch your desktop from for example Beagle to Strigi.
In the long term Xesam also aims for semantic services:
Concepts like value added services, tagging, and contextual- and related information are also among the buzzwords du Jour.
In the current state the project has released software tools to check servers/services for Xesam compatibility: the xesam-tools. The tools give you the ability to access the Xesam service by command line, however, some first unit tests are also implemented and will be extended in the future.
Also, an example server is part of the tools set which forwards all queries to the yahoo search page.
However, the Xesam project has difficulties to agree on a shared representation format for ontologies. Of course the KDE folks is in favour of an RDF storage just like Nepomuk-KDE is using, but some people would prefer an ini-like system. Additionally, reviewing the different possibilities takes quite a lot of time and the search tool developers are busy enough with their own projects already.
Last but not least, the project itself has problems coordinating all efforts and people because there is a project homepage missing. The naturally best place might be freedesktop.org, however an according bug report has not been answered yet.
In this regard the main question for the near future is if and when the project will agree on the ontologiss format – if that problem is solved Xesam might again gain speed to become a real standard for Free desktops (at least).