serial datatype changes for v7.3?

Hi,

I'm playing around with the CVS version and noticed a change from 7.2 in 
regards to serial datatypes - they no longer automatically have an 
index. Is this a deliberate thing? I did a search in the archives but 
didn't come across mention of the change. A pointer to discussion on 
this would be great.

CREATE TABLE author (
authorid SERIAL,
firstname VARCHAR(255),
surname VARCHAR(255),
dateofbirth DATE,
gender CHAR(1)
);

NOTICE:  CREATE TABLE will create implicit sequence 
'author_authorid_seq' for SERIAL column 'author.authorid'
CREATE TABLE

library=# \d author                                        Table "public.author"   Column    |          Type          |
                        Modifiers
 
-------------+------------------------+-------------------------------------------------------------- authorid    |
integer               | not null default 
 
nextval('public.author_authorid_seq'::text) firstname   | character varying(255) | surname     | character varying(255)
|dateofbirth | date                   | gender      | character(1)           |
 

library=# \di
No relations found.