Sven Krosse of the topicmapslab has implemented the current TMQL draft (from 2008-07-15) and his implementation has been checked into the Ontopia sandbox. It can be built with Maven (mvn package), but requires you to tell Maven where to find the current Ontopia .jar built from trunk. Once built the processor implements the same QueryProcessorIF interface as the tolog and Toma implementations, and so can be accessed from the Omnigator query plugin with some minimal configuration.
As the first external collaborator, Space Applications Services of Belgium has announced that they are joining the Ontopia project. Their intention is to use Ontopia in their ongoing Topic Maps projects, and also to lead the implementation of the TMQL standard and possibly also TMCL.
Here is the announcement in Space Applications Services’s own words.