Comment 5 for bug 1031836

As a workaround one can manually update the tzdata information:

1) Download the latest tzdata file:
mkdir tzupdate
cd tzupdate
wget http://www.iana.org/time-zones/repository/releases/tzdata2012e.tar.gz

2) extract the data:
tar -xvzf tzdata2009b.tar.gz
zic -d zoneinfo northamerica

3) Copy the relevant data to the approriate directory:cd zoneinfo
cd zoneinfo
sudo cp -r * /usr/share/zoneinfo/

4) Text the changes:
zdump -v America/Port-au-Prince| grep 2012

That should produce this output:
America/Port-au-Prince Sun Mar 11 06:59:59 2012 UTC = Sun Mar 11 01:59:59 2012 EST isdst=0 gmtoff=-18000
America/Port-au-Prince Sun Mar 11 07:00:00 2012 UTC = Sun Mar 11 03:00:00 2012 EDT isdst=1 gmtoff=-14400
America/Port-au-Prince Sun Nov 4 05:59:59 2012 UTC = Sun Nov 4 01:59:59 2012 EDT isdst=1 gmtoff=-14400
America/Port-au-Prince Sun Nov 4 06:00:00 2012 UTC = Sun Nov 4 01:00:00 2012 EST isdst=0 gmtoff=-18000

CHanges should be immediate, ie. reboot should not be required.

The above was adapated/sanitized from: http://chrisjean.com/2009/03/10/updating-daylight-saving-time-on-linux/

The above was tested in both Ubuntu 12.04 LTS and Trisquel 5.5.