I believe you need to install tempered glass or a glass specifically fabricated for this application since thermal shock can be an issue.

Here is a link that might be useful: thermal shock info

Another GWer, Montanamaven, painted her backsplash red and installed plate glass over it. It looks awesome, with the right type of glass, sounds like it might be something you would consider. Pictures of Montanamaven's kitchen are at the bottom of this thread:
http://ths.gardenweb.com/forums/load/kitchbath/msg0500562828929.html?43

I think metal behind the stove and glass for the rest would be nice. I've worked with glass, and can definitely see it cracking due to the heat. The heat expands the glass where it's hot and not where it isn't and the expansion has nowhere to go, so breaks the plane of the surface and cracks. Or something like that.

Do you have a separate panel over the stove? That might give enough expansion room. Or maybe do mirror tiles over the stove and sheet mirror elsewhere. Or something like that?

I have a mirror backsplash in my butler's pantry, but nothing much happens there...

I second the sheet of metal behind/over the stove. I think it would go well with the mirror and yet not crack. I can definitely see mirror cracking simply from the heat of the stove -- also check where the oven vents because heat can really focus there.

I have a painted wall with a plate glass back splash, but am putting stainless steel tiles in the small gap between my stove and the fan.

We used laminated glass for backsplash.

Thanks so much for all your replies. I plan to put some other material behind the stove and keep the mirror on each side. I'm thinking of either stainless steel sheet (like montanamavan)or SS tiles (the stove and venting microwave are both SS) or tempered painted glass (like pharaoh) or glass tiles.

I just started using this site and love it. I've spent hours looking at posting today! Still trying to get used to the format and learning how to post pictures.

Again - Thanks to everyone!
Candyce