This update provides 2012b which provides the following
important changes:

* Cuba has delayed start of DST by 3 weeks (now starts
April 1 rather than March 11
* Chile 2011/2012 and 2012/2013 summer time date
adjustments.
* Falkland Islands onto permanent summer time (we're
assuming for the foreseeable future, though 2012 is all
we're fairly certain of.)
* Armenia has abolished Summer Time.
* Tokelau jumped the International Date Line back last
December (just the same as their near neighbour, Samoa).
* America/Creston is a new zone for a small area of British
Columbia
* There will be a leapsecod 2012-06-30 23:59:60 UTC.