mapeo de psycopg2 Python:lista de dictados a Postgres:matriz de tipo compuesto para una instrucción INSERT

Ampliando sus esfuerzos solo un poco, ¿qué tal:

quote_1 = ("monkeys rock", "False")
quote_2 = ("donkeys rock",  "True")
q_list = [ quote_1, quote_2]
print cur.mogrify("insert into posts VALUES(%s,%s::quotes[])", 
                  ("animals are good", q_list))
#
#                 added explicit cast to quotes[]->^^^^^^^^

Explicación :

Si ejecuta:

insert into posts 
VALUES('animals are good', ARRAY[
    ('monkeys rock', 'false'),
    ('donkeys rock', 'true')
]);

directamente en psql obtendrás:

regress=# insert into posts 
regress-# VALUES('animals are good',ARRAY[
regress-#             ('monkeys rock', 'false'),
regress-#             ('donkeys rock', 'true')
regress-#  ]);
ERROR:  column "q" is of type quotes[] but expression is of type record[]
LINE 1: insert into posts VALUES('animals are good',ARRAY[('monkeys ...
                                                    ^
HINT:  You will need to rewrite or cast the expression.

Efectivamente, decirle a Pg que su matriz anónima es del tipo quotes[] hace el truco:

regress=# insert into posts 
regress-# VALUES('animals are good',ARRAY[
regress-#           ('monkeys rock', 'false'),
regress-#           ('donkeys rock', 'true')
regress-# ]::quotes[]);
INSERT 0 1

regress=# select * from posts;
       body       |                           q                            
------------------+--------------------------------------------------------
 animals are good | {"(\"monkeys rock\",false)","(\"donkeys rock\",true)"}
(1 row)