As you are no doubt aware, Daylight Savings Time has been extended by 4 weeks in the United States.  This means that your Windows Mobile devices will need an update to change the clock automaticaly on March 11, 2007 instead of in April.

Microsoft has released an article for each operating system.  These articles describe registry changes to be made.
How to configure daylight saving time for the United States and Canada in 2007 and in subsequent years on Windows Mobile-based devices
How to update daylight saving time for the United States, Canada, and Mexico in 2007 on Windows CE-based devices

Microsoft has also announced a tool to set the appropriate registery entries.  This tool does not appear to be available yet, but we'll keep you posted.  Each device manufacturer will probably release a CAB file or update tool for their devices, as well.

Microsoft has a Daylight Saving Time Help and Support Center with information on updates for desktop and mobile operating systems.