Not a good idea.
Think of it this way: The ground is the alternative path for the returning energy in the case that the neutral connection shall fail. If you tie these together, you've essentially screwed over your back up plan. Now the emergency return becomes your body.
Yes this could potentially become a fire hazard.
I generally tie my neutral to one of the tabs that connect the switch to the box, or just clip it to the box (I don't use plastic work boxes for any thing other than low voltage applications).
I know this is an over simplified explanation (yes I took physics as part of my E.E. degree), but is should suffice as to why it's not a good idea. Also, it could be mentioned that using the ground as a neutral can cause other outlet's ground to go positive in reference to grounded plumbing (I have seen this in my job as a home remodeling guy), and I know that in most places in this country the ground and neutral bar are one-in-the-same at the distribution center. There are, however, places that stipulate that ground is ground and neutral is neutral at the breaker box.
If you have a neutral in the work box where you are installing the switch, please use it. It will give this Fire Fighter/ EMTb piece of mind.