pgAdminIII will not allow you to add a self-referential constraint while using the GUI table editor, see the below example:
CREATE TABLE "role"
(
uid integer NOT NULL,
"name" character varying(32) NOT NULL,
parent integer NOT NULL DEFAULT 1,
CONSTRAINT role_pkey PRIMARY KEY (uid),
CONSTRAINT role_parent_fkey FOREIGN KEY (parent)
REFERENCES "role" (uid) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE RESTRICT
)
WITH (OIDS=FALSE);
ALTER TABLE "role" OWNER TO glasshook_admin;