I have written a small patch to enable a correct PostgreSQL health check
It works similar to mysql-check with the very same parameters.
listen pgsql 127.0.0.1:5432
option pgsql-check user pgsql
server masterdb pgsql.server.com:5432 check inter 10000
The patch has been commited to 1.5 tree.
You can use it against 1.4 tree without any problems.
Moreover, I have submitted the FreeBSD PR to 1.4 port in ports tree as well.