Timezones -- what comes out does not go in?

The timezone on our boxes is set to Etc/UCT (possibly a distro default).

(psql 8.1.4)

=> select to_char(current_timestamp, 'HH24:MI:SS TZ');
   to_char
--------------
 09:05:48 UCT
(1 row)

=>  select '09:05:48 UCT'::time;
ERROR:  invalid input syntax for type time: "09:05:48 UCT"

UTC works, of course:

=> select '09:05:48 UTC'::time;
   time
----------
 09:05:48
(1 row)


Is this behaviour expected? Desirable?

Thanks
Julian