Geekzone reports that a service called Roaming Messenger will incorporate GPS-awareness with instant messaging using the RIM Blackberry 7520. The service is designed for first responders, corporations, and utilities that want to leverage text messaging services in addition to or in lieu of voice.

Roaming Messenger claims to provide these capabilities with "end-to-end, government-grade security". It seems like a very deep offering at first glance. I've never heard of this company before, but I think I'll do some research on it and see if they've already deployed to a paying customer in the United States.