Impactful packaging, but seems gimmicky. Also, think about it from a supply chain perspective: water is heavy . Conservatively, assume the mp3 player in normal packaging is about a pound. 16oz of water is going to double that. And distribution channels for consumables is completely different from electronics. I can't imagine this is going to be widespread.
Bigger problem is that once you buy it, you still need to take it home, dry it off, and load music on it.