This question is related to this other question.
After you have jailbroken your device, you have root access to your device and so do apps that you install.
Can you change the account that an application runs with after you have installed it? This would allow to use an account with less privileges.
If it's possible, then how do you grant/revoke access to data (address book, emails, settings) and APIs (install keyboard hooks, issue network request)?