CREATE TYPE ntt_varchar2 AS TABLE OF VARCHAR2(4000);
/

--8i
SELECT *
FROM   TABLE( CAST( function_that_returns_array() AS ntt_varchar2 ) );

--9i
SELECT *
FROM   TABLE( function_that_returns_array );

--Loading ( useful for bulk loading collections "in-line" )...
SELECT some_table.col
,      CAST( MULTISET ( SELECT my_table.my_col
                        FROM   my_table
                        WHERE  my_table.key = some_table.key )
         AS  ntt_varchar2
FROM   some_table;