The ROS release pipeline works in several stages.
When a maintainer makes a release, the package will be built and available on the test/shadow repository. You can monitor the status of the various repositories via the status pages (e.g this one for Kinetic on Ubuntu).
After a couple weeks in the testing repository without reported regression, we will announce the upcoming sync via a thread analog to this one.
It will then be synced to the main repository and the summary of the sync is announced on discourse: New Packages for Kinetic 2018-03-15.
In this particular case, as a new version of navigation has not been released, it’s not available on the testing repository yet, hence was not been part of today’s sync.