According to Apple, after six wrong password tries, the iPhone displays a message that it has been disabled. This protection works the same way with iPads and iPod Touch devices.
Apple recommends two ways to try to correct this problem. If the phone has been synced to iTunes, it should be connected to its syncing computer. Opening iTunes often syncs, backs up and restores the phone. If the phone has not been synced to iTunes but the "Find My Phone" service is enabled, "Remote Wipe" erases everything on the phone. After this has been completed, backup information stored on the iCloud allows the password to be reset.