I'm not sure about the existence of any standard scripts, but we have a pair of checks running periodically on the backup server.
This shouldn't return anything:
tail -3 /var/log/postgresql/postgresql-9.1-main.log | grep FATAL
And this should return something:
ps -u postgres -o cmd | grep "postgres: wal receiver process streaming"
These have worked very reliably for many months.
-John