Title says it all. Can I buy AppleCare and get a free replacement? Also I think the phone is weaker, there is no way the phone should shatter from a 4 foot drop
Depending on when you bought your phone (if it's less than 30 days old I think you're still eligible to purchase), you may be able to buy a SquareTrade warranty and then make a claim in a couple weeks. They cover shattered glass.
I bought my 2-year ST warranty for $84. If you buy that warranty and then file a claim for replacement, I think they'll get you for a $75 deductible. You'd essentially be paying $159 for a new phone but you'll have the coverage for two years. I think that's a pretty solid option.