Joe,
Is it too difficult to store this info? I wanted this feature for long term memory.
Storing that data inside the photos themselves would be problematic for a few reasons. One, you may not want your client to be able to tell where you have previously uploaded your photo. If the upload status were written to the XMP data, your client could simply open up the image in Photoshop and see this info. Two, this data could get rather large (depending on how much each entry took and the number of times the photo were uploaded). Three, depending on how you did the upload operation, the file you selected may not at all be the photo that was uploaded, rather a scaled derivative was sent. So should the file that was selected be updated with the persistent upload info, or should the file that was actually uploaded contain the upload info?
In any rate we have decided not to make this data persistent for a variety of reasons. You can keep the Upload logs if you like and they'll contain this history.
-Kirk