So, ordinarily, iPhone is supposed to appear in your iPhoto list, as pictured. But what if that doesn't happen, and you've tried everything: erasing iPhoto settings, playing with iTunes preferences… everything, in fact, except erasing your iPhone's valuable data? How to sync photos into iPhoto again; that is, how to get your iPhone to introduce itself as a camera once again?
As strange as it may sound, this is caused by you downloading picture attachments or choosing Save image in mobile Safari. So just go and mail yourself every photo from Camera Roll that was not created with iPhone's own Camera, and then delete them.
That's right, just go right ahead and delete all the photos you downloaded from your iPhone's Camera Roll. This'll restore your access. This has worked on my iPhone 2G with OS 3.1.2.
Well, if it doesn't help you, you could also try something else from this thread on MacRumors forums.