In the United States, the military is looking at issuing their troops with mobile phones. A section known as the Army Capabilities Integration Center (ARCIC) is investigating ways that the Army may be modernised, and that includes the use of gadgets like smartphones, pads, and the like.
As well as the more obvious use as a phone, they’re looking at using these devices to provide access to secure areas (as an access card), and viewing images from, for instance, a drone that may be flying near a nearby area of interest.
Obviously such things as security and encryption will need to be up to par for the military.