Timestamp confusion

Greetings!

I have a table with a column declared to contain a timestamp with time
zone. A database function inserts a row into this table using the
following statement:

insert into alarm_hold (charge, hold_code, hold_generated,
condition_date) values (ChargeNum, '0471', 0, current_timestamp at time
zone 'UTC');

The resulting value contained in the timestamp field is 2010-09-28
13:09:27.015-04.

Since I am in the Eastern time zone of the United States and daylight
savings time is in effect, the -04 indicates that it is 4 hours earlier
for me than it is in Greenwich, England. And this value was generated
at 9:09 this morning local time, so the 13:09 is understandable.

The thing I am confused about is why the "-04" is there. This timestamp
should show a UTC time. But with the -04 in there, it seems to me that
it is showing an Eastern Daylight Time time.

What don't I understand?

Thanks very much!

RobR