Software
The g-code interpreter runs on an embedded MCU, either an ARM (LAOS) or an AVR (GRBL), and takes care of the realtime work of controlling motors and the laser.
The watchdog will be a simple control loop running on a separate AVR which ties into the interlock and does monitoring of all the high-level sensors in the machine to shut down everything if anything goes wrong.
Like LAOS we'd like to use general purpose software like Inkscape in stead of specialized laser cutter software, so we will use LAOS' postscript-to-gcode converter, there might need to be some way to parameterize the g-code it generates so it's possible to adjust power-levels at the machine (without a simple potmeter)
Only people who've been properly trained should be able to turn the machine on, we'll integrate with the existing access control system at OSAA: HAL900 so a user can unlock the machine using his RFID.
To avoid having a crummy little display and keypad on the machine, management of the machine will be done via a web interface, to begin with we'll just mount a laptop on top of the enclosure which has been set to display a browser in full screen which shows the machine-management page from the server.
The laptop might go away at some point and be replaced by a proper embedded PC inside the enclosure, but this is a minor point.