Invalid daylight saving time (DST) information in Windows Mobile devices

As of March, 2011, the Windows Mobile cumulative update for daylight saving time (DST) December 2009is the latest DST update for Windows Mobile-based devices (versions 6.5 and lower).  Any changes made to the normal schedule of DST transition times included in the December 2009 update may not be reflected accurately in these Windows Mobile-based devices.  Effectively, there may be an overlap period for some time zones when the transition into and out of DST are not accurate.  In some instances, the time on the device may be incorrect by the amount of the current DST offset, usually 1 hour, during this period. A current list of new / modified time zone information (TZI) keys is included in Microsoft KB article 914387.