As I mentioned in a previous post, Preparing for DST 2007, the change in the dates of both the start and the end of daylight saving time (DST) will impact the Calendar of Outlook/Exchange users.
Microsoft is releasing several patches and update tools. Yesterday they released a new one: Microsoft Exchange Calendar Update Tool. And it comes with a very descriptive KB article: How to address daylight saving time by using the Exchange Calendar Update Tool.
The Exchange Calendar Update Tool enables administrators to update, using the Time Zone Data Update Tool for Microsoft® Office Outlook®, multiple user mailboxes, thereby avoiding the challenges involved with broadly deploying the Outlook Time Zone Data Update Tool to all end-users.
Before you run the Exchange Calendar Update tool, refer to Microsoft Knowledge Base article 930879, "How to address daylight saving time by using the Exchange Calendar Update Tool," for complete information about potential effects on your IT environment and user base.
After installing the Windows and Exchange daylight saving time (DST) updates, all old appointments (both recurring and single instance) that occur during the extended DST period will be incorrectly displayed as having moved back one hour. These appointments will need to be updated so that they display correctly in Outlook, Outlook Web Access, and CDO-based applications. The Outlook Time Zone Data Update Tool enables end-users to update their own calendars. (For Outlook 2007 the time zone update feature is built into the application.)
The Exchange Calendar Update Tool enables administrators to avoid the challenges involved with broadly deploying the Outlook tool to all users and ensuring that each user runs the tool correctly.
Paul is blogging a lot about this subject. If you're concerned about DST changes, be sure to read his blog!