I thought about that but mount it on a moving platform and the software sees the whole image as movement and the turret goes insane.
There could be a simple solution... Keep the turret servos 'off' by default. Find some facial/body recognition software and have it scan the moving camera image. When it gets a hit, have it cut power to the bot and turn the turret power on.
It's a good brute-force approach to take but you still couldn't have it moving fire while moving. The only real way to do that would be software that controls the turret using a 'human form' tracker, and even that would be prone to attacking Jesus statues and Justin bieber posters.