http://bugzilla.wikipedia.org/show_bug.cgi?id=505
See also
http://meta.wikimedia.org/wiki/Automatic_timezone_selection -
for comments
In four weeks, most of the US states and also European countries will
change to daylight saving time ("Sommerzeit") --> timezone offset of
many users need to be adapted individually.
What I proposed within this enhancement report was, to switch timezones
automatically according to the affected countries (for users who have
opted-in such a new method).
T.