I was checking out "The Official Source for Your Navigation DVD Updates" to see if there was any new information/map data for our 2006 Honda Odyssey. Currently I have Version 4.31 and the latest version is 4.56.
I did notice this information about DST in the FAQ:
The navi is not switching Daylight Savings Time correctly anymore (in March/November), or the navi is still switching the time using the old April/October daylight savings schedule. What's wrong?
A new software version will be available soon that can be loaded by your dealer to change the navi's old Daylight Savings Time schedule to the new March/November schedule.
So it looks like we won't have to pay for an entire Navigation DVD update to patch the system with the new dates. I'll ask the dealer about it at my next service.