I learned one photo lesson during a family trip to DC - set all cameras to local time.
Aperture has some time zone support, but it's inconsistent. For example, time zones don't appear in the adjusting date/time dialog, but they do show in metadata.
iPhoto (8.x) has no time zone support. So 9am CT photos show next to 9am ET photos. If Aperture photos with different time zones are displayed in iPhoto date sort they can be out of sequence.
Time zones are evil, but iPhoto is eviller.
Update: The combination of end-of-life for iPhoto as we've known it (iPhoto '11 is a big regression) and this latest mess pushed me ever the brink. I've stopped using iPhoto as my image repository.
I'm going to use Aperture going forward, while slowly, painfully, migrating old images from iPhoto. It may take a year of tedious rework; Aperture doesn't import iPhoto event or album descriptions  for example. I'll have to copy/paste annotations from iPhoto Events to Aperture projects. Where I can't move an Album Description to an Event I'll create a sort-first 'key photo' and put it in the photo Description (wish there was an AppleScript way to automate this. 
 Aperture could store iPhoto Event descriptions as Project Info Descriptions (shift-I), but the import doesn't do this.)
 Possible hint: AppleScript to store Album Descriptions