On 18th of December Bruce Momjian committed very important, but relatively small, patch:
Log Message: ----------- Install server-side language PL/pgSQL by default.
There is no point in showing it, commit log tells all – basically from 8.5 on PL/pgSQL will be enabled by default in all databases.
There was time when people rejected “stored procedure" suggestions, because they didn't have any PL/, and installing them required superuser privileges. For some time (since 8.3) you no longer need to be superuser to create trusted languages, so the problem mostly vanished, but now, it will simply cease to exist 🙂