are long strings (500 char?) working?

I've tried using both PreparedStatement and regular Statement
modes with a 450 character string:

SELECT response, last_requested
FROM dataweb_response_cache
WHERE request = 'long string here'

and

SELECT response, last_requested
FROM dataweb_response_cache
WHERE request = ?
(PreparedStatement form)

and I consistenly get parse error around
LIKE or =  (I've tried both)

though the same query works fine in
short string form anyway with psql
(haven't tried long string form, will
if advised).  The short string I substituted
for the long string otherwise had all
of the quirks of the long string