Is this really the only way?
for f in `echo "\\z" | psql -u <suser> <database> | cut -d \| -f 2`; do echo "GRANT ALL ON $f TO <new-user>;" | psql -u <suser> <database>; done
(found on http://www.postgresql.org/idocs/index.php?privileges.html)
The problem is that the \zz doesn't seem to be useful for me...
mydb=> \zz
Access permissions for database "mydb"
Relation | Access permissions
----------+--------------------
(0 rows)