An IT Policy is the way a company enforces its IT Security rules on blackberries that have inside the firewall access. These devices have BlackBerry Enterprise Service (BES) accounts instead of the BlackBerry Internet Service (BIS) accounts that ordinary consumer users typically have.
BES users get OTA synching of their Calendar, Email, Address Book, Tasks, and Memos. In return, they accept that the company can monitor all their email, log their phone calls, and in general control every aspect of their phone: whether they can install apps, use the Media Card or Bluetooth, or access the internet, for example.
IT Policies can be severe, or very benign. Mine only requires me to use a password and sets the max timeout to 30 minutes.
If you have an employer-provided phone, and attempt to remove the IT Policy with CrackIT or any other tool, your attempt will be detected the next time you attempt to log on to the company servers, the IT policy will be pushed back on your phone, and you could face severe disciplinary consequences for violating security.