I remember something about that one... I had seen it on the store when searching for something else.
If I recall correctly, it doesn't actually give you any real security other than not obfuscating the location of those pictures. The only way I know of to actually make pictures "secure" is to put them in a TrueCrypt container or something comparable, but that would be on a PC.
I'll go do a store search and see if I can find it for you, and possibly a couple of alternatives. I'll post back with what I can find.
UPDATE 1: (more to come)
Media Locker Pro looks like a good one. Just search by the title and you'll find it just fine. It doesn't pretend to be something else, but is very secure.
UPDATE 2: (final)
I simply can't find another app on the store at this time that is even worth trying. They either have bad reviews, don't actually hide anything, or offer only a false sense of security. I was unable to find the app that looked like a different program. Sorry. Perhaps someone else will have better results.