I was planning to have a select few libraries on the disk image. If you are discouraging that based on security of accidental deletion or corrupt, I won't be overly worried as everything is backed up to DVD.
I just wanted to see if there was a way to make accessing the iPhoto libraries more secure so if I let someone do something on my PB my pictures are a little bit safer, as some are of a rather personal content.
iPhoto Buddy allows you to 'lock' a given library, however if the user knows anything of the file system and how to browse with finder, they can find the locaiton of the library and view the pictures this way, so it is not really locked by anything other than iPhoto Buddy, they just have to launch it another way.