I'm using iPhoto '09 and have an 80GB library. I want to back everything up to DVDs, because I figure that's the cheapest / most reliable solution. (I plan to have a couple of copies and keep them in different places.)
Ideally, after the initial backup, every couple of months, I'd back up everything that's changed (new photos, edits, metadata) to single DVD and add it to the set.
How would you go about doing that?