During the upgrade from iPhoneOS 2.2 to 3.0 a lot of things went wrong, and I ended up wiping the iPhone, reinstalling iTunes and in that process deleting all the backups.
Luckily I had a 'file' backup of all my data.
To restore the "camera roll" images on your new iPhoneOS 3.0 you can follow these steps:
SSH into your iphone and upload all the JPG files in
/private/var/mobile/Media/DCIM/100APPLE.
Then upload all the THM files in
/private/var/mobile/Media/DCIM/100APPLE/.MISC
Set the owner of all those files to "mobile".
Fastest way is via an command line SSH client à la Putty.
Browse to
/private/var/mobile/Media/DCIM/100APPLE
and use the following command:
On iPhoneOS 2.x the JPG files and THM files were in the same directory.
iPhoneOS features BTH files in the .misc directory too, my guess is that these are cache files of photos in the iPhone's screen resolution.