Thinking aloud here, not providing answers yet...

- does this need to be done at camera / application level? Can it be done at filesystem level? We want to react when a photo is successfully written to a filesystem, not to the photo being taken and processed.

- I appreciate that we don't want to run rsync from cron for power/bandwidth reasons, but could we create a watched directory to which the camera saves and a way of (doing arbitrary thing) to back it up? Could it be based around inotify/incrond? (http://www.cyberciti.biz/faq/linux-i...e-directories/)

If that provides the trigger, it should be pretty easy to whip up scripts to sync new files to [rsync|webdav|whatever]. Is there still a need to build it specifically into or around the camera?

Edit: we seem to have inotify-tools, which provides inotifywait; this could be used to detect close-of-write on a new file in the camera directory. What we do from there is open to debate...