I remember looking into this back in the day (I was 16 once
![Smilie](/tfp/images/smilies/smile.gif)
). There are several Sony models that had the ability to do this out of the box (I infact had owned one, accidentally drove over it with a truck though... ask me and I'll tell you the story), you might still be able to find them on ebay. Nowadays... I think you have to modify the optics internally to stop the filter (that is in all of these nightshot cameras) from disengaging in regular light scenarios.
There was also some problems with the camera's built into cell phones, that featured this technology. It lead to the banning of camera phones, in many schools all over the world. Those 16 year olds will get you every time.