As far as I have been able to tell, this is a problem that afflicts all photo apps from independent developers.

My typical workflow when taking pictures with my iPhone is something like this:
1. shoot
2. edit/cull
3. upload to flickr
4. save to iPhone's "Photos" app
5. sync to iPhoto when I get home

Here's the thing: any metadata I added for flickr is lost on step 4. Worse, the GPS coordinates are also lost, and are quite a bit more difficult to reconstruct, if I want to.

I don't know if these 3rd-party apps can embed this metadata as IPTC data in the image files, and if so, if iPhoto would parse that data. But it's definitely a shortcoming in this process.

Anyone know if it's even possible for 3rd-party apps to embed this metadata in a portable way? I've been using Camera+ and like it, but it and every other app I've tried, apart from Apple's own, does not deal with metadata well.

Filterstorm is coming for the iPhone soon and supports editing of IPTC data.

Adam - for the apps that save to the camera roll, this is not their fault. Apple still hasn't added the necessary API to embed metadata in images saved that way.

Apps that have options to email/upload images someplace else can manually inject metadata and send it along, but obviously this is a lot of extra work, and each app ends up with a different workflow.

Paul—Thanks. I'm disappointed but not surprised to learn that, since it seems that if it were possible, someone would have done it.