Does Jailbreaking unlock private storage on my iphone 4?

I want to know if there's storage the iphone won't let me use such as the "Private storage in Cydia? Is that storage real? Is there a way I can use that? If so, How?

Jailbreaking removes all sorts of restrictions, but you need an app to take advantage of that. Normally iPhone apps can only access their own private storage, but once a phone is jailbroken they can access other things. However, they have to be written to do that, so it depends on which app you are using.

Of course, when any app can access storage belonging to another app, viruses can waltz onto your phone in no time, which is why Apple doesn't allow this in a non-jailbroken phone.