If it's small enough, it might be able to be buffed out. I would go to your local automotive parts store, and see if they have the proper glass cleaner. A dremel tool with the polishing wheel, and the solution, should do the job.
I'm going to PepBoys in the morning, and I'll try to find out exactly what the stuff is called.
Rich
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Member MAXC, NEXTerra
http://www.xtremexterra.com