To updated the timezone files:

1- get the vzic or tzurl tool from http://code.google.com/p/tzurl/source/checkout and compile it

2- get the zone files, for example:
  
  mkdir /tmp/zones
  cd /tmp/zones
  wget ftp://munnari.oz.au/pub/oldtz/tzdata2011n.tar.gz
  tar -zxvf tzdata2011n.tar.gz

3- run the conversion tool and adjust the PRODID

  vzic --pure --olson-dir /tmp/zones/ --output-dir SOGo/SOPE/NGCards/TimeZones/
  cd SOGo/SOPE/NGCards/TimeZones/
  rm -f zones.h zones.tab

  find . -name "*.ics" | xargs -ti sed -i s/'My Organization\/\/NONSGML My Product'/'Inverse inc.\/\/NONSGML SOGo'/ {}
  find . -name "*.ics" | xargs -ti sed -i s/'\/myorganization.org\/20120508_1\/'// {}