I have not seen much about the idea of using laser scanners for real time security, but in this article the author builds a case for the benefits of using 3D laser scanners for perimeter protection. Trygve Behny is a marketing manager for Sick, a laser scanner manufacturer based in Germany.
A couple of the interesting applications include a laser scanner integrated with auto-tracking cameras. In this case if an intrusion is detected, the camera will automatically follow the intruder as they move through the protected area, keeping the intruder in sight and allowing for more accurate identification of the threat. Another frequent configuration is GPS mapping, which can be used to display and track the location of the threat on a building blueprint or property map using GPS coordinates.
The author claims that laser scanners can perform better than cameras in rain and snow which perhaps for security purposes is fine, but for higher accuracy apps this is not usually the case.