iPhone picture privacy app I am looking for a picture privacy app supporting the following features:


Unlimited number of "vaults" (note: only one vault is bad, one real vault plus one fake vault is bad as well, only an unlimited number really allows to hide vaults and to use the app with several groups of people)
Folder support per vault
Full screen mode
Picture zoom
Picture slideshow and manual forward/backward with low decoding delay
Mass upload
Great, well designed, visually appealing user interface


Do you have any idea or recommendation?

Thanks!
If you're looking for privacy, I've heard about an app called Ben the Bodyguard that's going to be released soon. Judging from their intro page, it will probably meet your "well designed UI" requirement.

Apart from 3rd party apps like that one, iOS is not really designed for multiple users. Use a lockscreen PIN and don't share the phone if you want privacy in the meantime.