The security system in LinuxMCE is very flexible, in particular:
You can choose to interface to an existing panel. a Driver for an Apex 6100 alarm panel is provided. This driver is written as a GSD Ruby device, so its code can be exposed via the web admin.
Or you can choose to wire sensors directly to LinuxMCE and have it act upon those sensors directly.
In essence, regardless of which method you choose, LinuxMCE is polling the sensors for changes, updating itself and triggering events when the sensors are tripped.
Currently, with ZWave, the only sensor type supported is the passive-infra-red (PIR) sensor, which can be used usually to feed motion events to trigger alarms etc. To give a simple example:
* A Z-Wave motion sensor is placed opposite a Panasonic IP camera, and is linked to the camera in the web admin. The sensor is also set to trigger "Security" events when the house is in one of the armed states (either Armed, or Armed Extended-Away). So when the sensor is tripped, the system takes a picture, sends it to the mobile orbiters (and calls them), and keeps a record of the security event as well.
In addition, a GC-100 can be used, simply connect the sensors such as contact sensors, generic dry-contact motion sensors, etc.. to the individual sensor ports (there are 6 of them on the big GC100), and tell LinuxMCE what sensor is connected to which port, and place them on the floorplan.. The resulting sensors can then be used to trigger things based on events, etc.
So you don't even really NEED a dedicated security panel at all...for any reason... I guess some people like having an extra panel lying around.. I sure as hell don't.