Was looking for full encryption for my N9 and this thread came up.

Just thought I should add this talk: Blackhat 2012 EUROPE - Secure Password Managers and Military-Grade Encryption on Smartphones

In short, the vast majority (pretty much all) of the top apps (free + paid) in iOS / Blackberry that do this folder/file/input "encryption" either don't actually implement it properly or at all - I believe it was under 24hrs with one PC for all of them if you use a 6-7 digit passcode that consists of characters from the entire english keyboard (~96 characters).

Amusing talk if your interested in that kind of thing btw; being a complete beginner looking into the field, I really enjoyed it. Don't know what the situation is with our apps here, but good to keep in mind.