End User Computing: Protecting Data From the Device

Some of us have multiple cloud endpoints in the form of mobile devices all trying to access our personal and corporate data to do our daily jobs. These incredibly useful devices (smartphones, tablets, etc.) are now a part of our organizations life. So how do we protect our data from them. IBM recently took a draconian measure of banning Siri from their employees iPhones. Yet, how can they enforce such a measure?