original posting at http://technet.microsoft.com/en-au/bb821275.aspx
On 16 May, Western Australians rejected by referendum a proposal to extend their trial of daylight savings. As a result there will be no daylight savings in WA this year or for the foreseeable future.
This change will affect Microsoft Windows, Microsoft Office Outlook and other Microsoft, third party and custom applications, which are currently programmed to adjust their clocks on 25 October 2009. However, we have taken important steps to help you proactively address the issue.
The Australia 2009 Daylight Saving Planning Guide provides detailed guidance on preparing Microsoft solutions in complex environments for changes in daylight saving. Click on the links below to download the document in your preferred format:
What is the impact of Daylight Savings changes?Effects can range from the incorrect time display on the clock, to calendaring problems, to changes in business critical services that are time dependent.
What is affected?
What do I need to do?Thorough planning and testing for these changes is critical to ensure the change results in minimal user impact, so to help customers prepare Microsoft has developed the Australia 2009 Daylight Saving Planning document which details the nature and impact of the DST changes, along with planning guidance to avoid user impact.
What if the systems have been previously patched?Where servers, workstations and mobile devices have been added to the infrastructure, organisations will need to audit their environment to ensure all systems are updated according to the organisation's Daylight Savings Plan.
Where the environment does not have a consistent Daylight Savings Time (DST) update level, appointments may have been created with a mix of correct and incorrect DST transition dates.