I suspect the majority of water damaged iPhones that are replaced by Apple (refurb replacement, typically $200) have spent some time in a white water filled bowl. I don't have hard data, but that fits the anecdotes I read. I've come close myself.
Interestingly, Apple, offiically, will not service a toilet phone. Biohazard. (Scientifically I believe a flushed toilet is actually less of a biohazard than the human nose, but I'm working on memory here.) So there must be a lot of 'don't ask don't tell' going on.
FWIW, this blog post reviews the situation with an initial story and some updates:
For me the interesting bit are the rumors that the iPhone 5 will have a Liquibase or Hz0 like coating. Doesn't make it waterproof, but makes it very water resistant. Forget NFC and LTE or biggers screens or faster CPUs, for me the killer feature would be water resistance. (And I've yet to lose an iPhone to water -- though I came close in a table water spill.)