Depends on how deep they are. There are a couple of solutions I've tried, some better than others. If the scratch isn't too deep good old polishing compound under a buffer will do it. I've used rubbing compound too for deeper ones.
There is a kit available in most of the catalogs that comes with glass polish and a special polisher for use w/ a drill. I've been hesitant to get it, afraid of hurting the glass, but I'm sure some other members have used it and will tell you about it.
If you can hang your fingernail on the scratch, you're probably out of luck. If not, you should be able to polish it out with a specific kit for this. Eastwood Co. sells one at $33, part# 40011. You can use a drill or a low speed grinder. The most important thing is to make sure that you don't heat up the glass, because it will crack. Don't ask me how I know.--Bullitt
I have marks from my windshield wipers (no.. not me - old owner ARGH!); otherwise my windshield is good. You can feel them but they are more like a wide "rub" then a scratch - but they span most of the windshield. Am I just resigned to replace it or do you think there is any hope of polishing them out?