I got around the problem by changing the Windows Last Modification Date. To be more precise I did the following:
1. Select all photos in the Windows Explorer.
2 Right click and choose the Properties option.
3. Select the Details tab.
4. Add a bogus title to the photos
5. Click Accept.
As you can see, the Windows Last Modification Date has been updated and you have not changed ta single pixel of the photo.
Now remove the iTunes Photo Cache folder, change the photo synch folder in iTunes to an empty directory And synch. This will remove Ll synched photos from your iDevice. Now restore the photo synch folder in iTunes and resynch. If all goes well, all photos are now in alphabetical order of file name or by Date Photo Taken EXIF Property (dont't konw exactly on what iTunes falls back when the Last Modified Date is the same).
What I would like to know is, why photos were correctly sorted by EXIF properties in iOS 4 and iTunes 10.4, but by file modification date in iOS 5 and iTunes 10.5. I dont even know who is to blame: iOS or iTunes.
Brgds, Marc