Being brought up in India, we never have to worry about Daylight saving chores. But its very interesting and also important for any system designer to know all about DST.
More info at this link : http://webexhibits.org/daylightsaving/
DST also comes into play when we schedule jobs using cron or Quartz.
For e.g. In the US, many states implement DST at 2 a.m.
If we have a job scheduled at 2.15 am, then it won't be fired on the day when the cock is shifted ahead from 2.00 to 3.00 am :)