[SQL/BUGS] (possible) inconsistent behaviour of timestamp?

Here's an "interesting" timestamp related postgreSQL quirk:

testdb2=# select "timestamp"('now');
timestamp
----------------------------
2002-11-26 13:47:12.454157
(1 row)

testdb2=# select 'now'::timestamp;
timestamptz
------------------------------
2002-11-26 13:47:34.88358+00
(1 row)

testdb2=# select timestamp 'now';
timestamptz
-------------------------------
2002-11-26 13:47:47.701731+00
(1 row)

The first SELECT returns a 'timestamp', but the next two return a
'timestamptz' (presumably with timezone); is this inconsitent behaviour?

Cheers,

Stuart.
Royal Veterinary College
London, UK