According to ifoAppleStore, Apple is now offering replacement iPhones to customers who bring in their water-damaged devices for only $199. The replacements are refurbished - but still a great deal compared to havign to buy a new one and extend your plan with AT&T.
It has been known for awhile that iPhones have the ability to detect if they've been damaged in water. There is a white disc in the headphone slot that will irreversibly change color when entering in contact with water.
Now, that isn't a death sentence to your wallet.
You still have to fish that thing out of the toilet though.