BUG #1921: NULL<>NULL ?!?!?!?!?!?!?

The following bug has been logged online:

Bug reference:      1921
Logged by:          BogDan Vatra
Email address:      bog_dan_ro@yahoo.com
PostgreSQL version: 8.0.3
Operating system:   win xp pro
Description:        NULL<>NULL ?!?!?!?!?!?!?
Details:

Please execute this query:

create table test (id serial, tt varchar(50));
insert into test (tt) values(NULL);
select tt from test where tt=NULL;

This should return 1 row but ...
An then try

select tt from test where tt<>NULL;

0 row(s) !!!