Found the problem I was seeing... acs-subsite.info refers to a couple of .sql files which do not exist in the CVS tree for PG, only for Oracle.
I'll email the acs-subsite porter. Meanwhile, the workaround is to delete or comment out the two lines:
<file type="query_file" db_type="postgresql" path="www/admin/group-types/change-join-policy-2-postgresql.xql"/>
<file type="query_file" db_type="postgresql" path="www/admin/group-types/change-join-policy-postgresql.xql"/>
which are lines 138 and 142 of the packages/acs-subsite/acs-subsite.info file.
