Hi all. I did a quick search and didn't see this listed, so here it is.[Link: yamaha.com]
It's a very small app that's only useful for three amps: RXV-3900, RX-V2065, and the RX-Z7.
It's not 'fully featured 'by any means, but it gives you the power to turn on/off zones. It communicates via WiFi, so it's using the TCP/IP method.
It's also useful if you're developing for another remote (e.g. the Pronto) to work out how you can best manage sound.
It's only available in the US iTunes store, which is rather annoying.