last UPDATE or INSERT time of a table? - Mailing list pgsql-general

Is there a way to check the last time a table was UPDATEd or INSERTEd?
Is there a timestamp somewhere in the system tables?

(If not that would be really useful to help in web page cacheing and
expiration to learn if any change occured on the data)

Thanks in advance,
--
 HIPPOLYTE: Mais si quelque vertu m'est tomb�e en partage,
            Seigneur, je crois surtout avoir fait �clater
            La haine des forfaits qu'on ose m'imputer.
                                          (Ph�dre, J-B Racine, acte 4, sc�ne 2)