Timestamp + Interval time zone issues

[Mike Ginsburg]

So I have pg 8.4.3 installed, with a database set to EST5EDT time zone.

When I run "SELECT NOW()" I get
07/28/2010 14:27:07.767286 EDT

showing that the timezone is properly set up.

When I then try to add an interval to a statically entered time stamp, 
it gets all strange:
SELECT '01/03/2011 16:00:00-04'::timestamp with time zone + '-1 
hour'::interval;
        ?column?        
-------------------------
 01/03/2011 14:00:00 EST

Any idea why the adding of the interval is converting the result into 
EST instead of EDT?

Mike Ginsburg
Collaborative Fusion, Inc.
mginsburg at collaborativefusion.com