And, along similar lines, I have been able to install and start the squeeze version of incron (subject to satisfying a dependency on adduser, and listing relevant users in /etc/incron.allow). It'll need the startup script replacing with an event.d version, but I think that porting incron to maemo might well be the way to go.

This would allow for a filesystem event-driven daemon with a crontab-style interface, geared up to monitoring arbitrary directories for specific filesystem events and executing arbitrary commands when they happen. That could handle photo backup with and without microSD card, per-file or rsync, whatever. I'm not sure I can package it for Maemo, but that would look like the obvious solution...

Edit: incron is potentially interesting in its own right and I have spun off a separate thread for discussion of implementation and usage, in which the first example is for photo uploads.