Talk to Apple -- preferably, bring your iPhone into a local Apple store. If they have any supplies and it's clear the break wasn't deliberate, they should give you a replacement.
Calling Apple on the phone will help if you're not close to a shop, but it'll take longer to get a replacement.
I got it on the day of release and the touch screen died...This is not good...Has anyone else had theirs fail? Who should I send it to?