The trunk is now the place to put bug fixes for the next minor release. Development of additional features, or more major restructuring, should be put in separate branches.
Versions 1.6 and (soon) 1.7 are minor bug-fix releases based on version 1.5. They come from what is now the trunk, but was then the branch ktjet-v1r5-bugfixes in the subversion repository.
Branch ktjet-v1r5-vectorrehack contains Andy's version without the dependency on CLHEP.
Branch ktjet-conejet contains Will's work on implementing the cone algorithm within KtJet?. However, at the moment it seems this may not give the same results as v1r5 when using the Kt algorithm, so it hasn't yet made it to a release.