PSQL Engineering have recently released two updates to PSQL v11:
Both updates are for Windows and Linux versions of PSQL and should be installed on top of existing instances of PSQL v11. No uninstalls are required.
There are some new features included in the v11 SP3 Update 4 patch, which are documented in the Readme file.
You can download these patches and view the Readme files from PSQL Downloads.