This question was asked on the PostgreSQL novice newsgroup recently and Tom Lane fielded the question. Its a common thing to want to know if you are using the new 8.3 Enum feature. So we felt it useful to restate it.
Question: Given an enum, is there a query you can run to list out all the elements allowed by the enum?
Below is just a regurgitation of the news item http://archives.postgresql.org/pgsql-novice/2008-12/msg00043.php
CREATE TYPE myenum as enum ('red','green','blue');
WHERE enumtypid = 'myenum'::regtype
ORDER BY oid;