The way it works via iCloud is a little different then syncing your Mac. iCloud uses Photo Stream to upload from your iPhone/iPad2 to the cloud and then to your other devices you are signed into your iCloud account with. It keeps the last 30 days in the cloud. Although I never tested the iPhoto 9.2 Betas, I saw no difference in syncing multiple devices to iPhoto manually, so I would doubt there will be any change in that, once iPhoto 9.2 is released.