psql bug or feature?

I don't understand following behavior of psql:-)
This is PostgreSQL 7.1.2 on Linux.
--
Tatsuo Ishii

$ psql pgimage
Welcome to psql, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help on internal slash commands
\g or terminate with semicolon to execute query
\q to quit

pgimage=# \lo
List of databases
Database | Owner | Encoding
-----------+---------+----------
ascii | t-ishii | EUC_JP
foo | t-ishii | EUC_JP
foo1 | t-ishii | EUC_JP
latin1 | t-ishii | LATIN2
pgimage | t-ishii | EUC_JP
template0 | t-ishii | EUC_JP
template1 | t-ishii | EUC_JP
test | t-ishii | EUC_JP
testdb2 | t-ishii | EUC_JP
(9 rows)

\l: extra argument 'o' ignored
pgimage-# \lo_list
Large objects
ID | Description
---------+-------------
2401715 |
2401723 |
2401726 |
2401739 |
2401742 |
2401754 |
2401757 |
(7 rows)

pgimage-# select * from pg_database;
ERROR: parser: parse error at or near "m"
pgimage=#