Check out Microsoft KnowledgeBase Article 970653, "August 2009 cumulative time zone update for Microsoft Windows operating systems", which the Windows team just posted.
A nod to the good folks across our company working on our effort to help manage time (particularly in daylight saving time and time zone changes) documented and followed at http://www.microsoft.com/time and over at the blog at http://blogs.technet.com/dst2007. Lourdes is coordinating the efforts on our daylight saving time and time zone updates and releases for current products across the various product groups at Microsoft. As noted, this is a tough job, to say the least.
So, back to the latest semi-annual release…
The update that this article describes changes the time zone data to accommodate daylight saving time (DST) changes in several countries, as outlined in this article. This update also includes other DST-related changes, time zone-related changes, and settings-related changes. Some of these changes have occurred since the products that are listed in the "Applies to" section were originally released.
The following changes were made since the previous Windows cumulative time zone update. This update was described in Microsoft Knowledge Base article 951072:
- W. Australia Standard Time: Fixes dynamic DST table for the W. Australia time zone.
- SA Pacific Standard Time: Removes "Rio Branco" from the display name of this time zone.
- SA Western Time: Changes the display name of this time zone from (GMT-04:00) La Paz to (GMT-04:00) Georgetown, La Paz, San Juan.
- SA Eastern Standard Time: Changes the display name of this time zone from (GMT-03:00) Georgetown to (GMT-03:00) Cayenne.
- Greenland Standard Time: Adjusts the dynamic DST table for the Greenland time zone.
- Morocco Standard Time: Adjusts the DST start and end dates for the Morocco time zone for changes after the prior cumulative time zone update was created (December 2008).
- Pakistan Standard Time: Adjusts the DST start and end dates for the Pakistan time zone for changes after the prior cumulative time zone update was created (December 2008).
- Paraguay Standard Time: Introduces the new Paraguay Time Zone with DST start dates and end dates after the prior cumulative time zone update was created (December 2008).
- Fiji Standard Time: Removes Kamchatka from the display name of this time zone.
- Kamchatka Standard Time: Introduces the new Kamchatka Time Zone with DST start dates and end dates after the prior cumulative time zone update was created (December 2008).
- Coordinated Universal Time: Introduces the new UTC Time Zone without DST after the prior cumulative time zone update was created (December 2008).
- Montevideo Standard Time: Fixes the dynamic DST table for Montevideo time zone for Windows XP
Registry subkey name
Display name
Daylight name
Standard name
DST start
DST end
W. Australia Standard Time (GMT+08:00) Perth W. Australia Daylight Time W. Australia Standard Time Last Sunday of October at 02:00:00.000 Last Sunday of March at 03:00:00.000 SA Pacific Standard Time (GMT-05:00) Bogota, Lima, Quito SA Pacific Daylight Time SA Pacific Standard Time No DST No DST SA Western Standard Time (GMT-04:00) Georgetown, La Paz, San Juan SA Western Daylight Time SA Western Standard Time No DST No DST SA Eastern Standard Time (GMT-03:00) Cayenne SA Eastern Daylight Time SA Eastern Standard Time No DST No DST Greenland Standard Time (GMT-03:00) Greenland Greenland Daylight Time Greenland Standard Time Last Saturday of March at 22:00:00.000 4th Saturday of October at 23:00:00.000 Morocco Standard Time (GMT) Casablanca Morocco Daylight Time Morocco Standard Time Last Sunday of May at 23:59:59.999 3rd Thursday of August at 23:59:59.999 Pakistan Standard Time (GMT+05:00) Islamabad, Karachi Pakistan Daylight Time Pakistan Standard Time 2nd Tuesday of April at 23:59:59.999 Last Saturday of October at 23:59:59.999 Paraguay Standard Time (GMT-04:00) Asuncion Paraguay Daylight Time Paraguay Standard Time 3rd Saturday of October at 23:59:59.999 1st Saturday of March at 23:59:59.999 Kamchatka Standard Time (GMT+12:00) Petropavlovsk-Kamchatsky Kamchatka Daylight Time Kamchatka Standard Time Last Sunday of March at 02:00:00.000 Last Sunday of October at 03:00:00.000 Fiji Standard Time (GMT+12:00) Fiji, Marshall Is. Fiji Daylight Time Fiji Standard Time No DST No DST Montevideo Standard Time (GMT-03:00) Montevideo Montevideo Daylight Time Montevideo Standard Time 1st Sunday of October at 02:00:00.000 2nd Sunday of March at 02:00:00.000 Coordinated Universal Time (GMT) Coordinated Universal Time Coordinated Universal Time Coordinated Universal Time No DST No DST
As noted in this article, Microsoft strongly recommends that DST and time zone updates be installed on all impacted systems, devices and applications to ensure consistency with current DST rules and time zone settings worldwide. Customers should review the product updates available and posted on this site and at http://support.microsoft.com/gp/dst_prodlist for the latest and updated information of Microsoft products affected by daylight saving time.
An important note for Consumers
For those customers (consumers, small businesses) wondering "Does this mean I have to install the updates manually?"
No. Generally, consumers should wait for the updates to be installed via Windows Update rather than download and install these from the DLC. And for end users who have their PCs managed by a central administrator, your IT folks will handle the distribution and updating of your PCs over the network. (When in doubt, ask. 😉
Additional information
Please note that where we have heard that changes may be coming to a territory but have yet to receive an official confirmation from a government, we indicate that the changes are "not yet confirmed."
As a reminder on our cadence (outlined here and in a prior post), our product teams are have moved to a semi-annual product update cadence (with provisions for out-of-band releases as needed). Following the Windows regular cadence for publishing newly legislated DST rules and time zone updates, our "Cumulative DST and Time Zone Updates" will be released in November/ December (to the Download Centre and via Windows Update respectively) for the coming calendar year; we also provide semi-annual updates (like this one) in the July/August timeframe as needed.
For each, the window closes for additional updates a few months (generally four to six) prior to the release date.
As I originally posted here, most Windows applications (and some services) reference the underlying OS for DST and time zone information, but some do not. The product and service groups with offerings that have internal DST or TZ references have agreed to follow the regular schedule for cumulative Windows OS DST & TZ updates. The regular Windows release provide a regular schedule for other product groups to follow, as noted in the DST & TZ Product Update Cadence policy. We hope that this will provide a more predictable way for our customers to anticipate and plan for our cumulative updates
Tags: Windows, Microsoft, Daylight Saving Time, Daylight Savings Time, RSS, DST; 18,000,000 (up from 3M six months ago); 20,400,000 (up >3M)
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There’s a lot of talk 
