Fully supporting portrait mode would require changes to the OS and all the various pop-up dialogs (flight planning, searches, airport-info, etc). And it may require flashing the bios (which is a much more complicated update procedure). This is still a reasonable and possible feature, but the development effort means it's going to be further down the feature queue.
There is another option that would be simpler: A portrait mode that only affects the map. So the map, instruments, buttons, etc, would be in shown in portrait fashion, but pop-up dialogs, menus, virtual keyboards, airport info page, etc, etc, would remain landscape. In your opinions, would this be a reasonable approach for the first pass at Portrait mode? Or would this just be silly...
-Walter