Is there away to output a time stamp in a specified time zone with the time zone indicator (e.g. EDT)

I'm referring to US time zones here.  I'd like to output a time stamp field in a specified time zone.  I'd also like to display the time zone (e.g. EDT) at the end.  Ideally, this output needs to adjust the numeric portions of the stamp for standard time vs daylight time and then display EST or EDT accordingly.  The switch between standard time and daylight time occurred on 3-11-2012.  So time stamps before 3-11-2012 should have EST at the end and those after should have EDT.

to_char(my_timestamp_field , 'MM/DD/YYYY HH12:MI AM TZ') will output: 03/12/2012
10:23 AM EDT

to_char(my_timestamp_fieldat time zone 'cdt', 'MM/DD/YYYY HH12:MI AM TZ') will only output 03/12/2012
09:23 AM

Because we'll be reporting events in multiple US time zones, we must let users know which time zone the output timestamp is in. 

Thanks,

Alex