Secret partition app?

I'm looking for an android app that has a "secret" partition feature that requires a different password so if you type it in it goes to the master partition, but if I want to go to one with only my mail account on it for security reasons, I type in another password. I figured out about such a thing from a book called "Big Brother" it was a great book. Also, the password should be able to use the default system built into android for the lockscreen so you don't have to use 3rd party unlocking systems so I can still use my pattern lock on my HTC Incredible 2. Also, I'm aware this would require me rooting my phone.