I have two ways of backing up my ZP installation and wanted to share it here. Perhaps it can be of use to someone:
1. I use WordPress, and ZenPhoto uses the same database as WP. Within WP I use the backup plugin which does a cron job every evening, making a backup of my entire database including all tables and delivers it to my gmail account.
2. On my harddrive I have an exact duplicate of the albums folder on the server. When I add new images I start by uploading them to ZP. When finished I move those images to the same folders on my harddrive.
This way nothing can go wrong, I hope... but I wait for the upcoming move/copy/rename function before starting to add filenames and descriptions