The physical unit has only volume controls and a mute button. Like other Sonos products, the S5 needs a wired router connection or a Zone Bridge unit, which is a U.S. $99.00 box that plugs into your router and then allows the S5 to be wireless anywhere in the house. You can add additional S5 units that only need AC power to work.
The S5 looks a bit like the Bose audio systems that dock with the iPhone. The difference with the Sonos unit is you keep the iPhone with you, and the S5 gets your music from iTunes.
The S5 will be available later this month for $399.00. If you already have a Sonos system in your home or office, or are just getting started with multi-room music, this system is worth checking out.
Of course Apple also provides solutions to stream iTunes with the Airport Express Air Tunes hardware/software. Apple also offers Remote, [iTunes link] a free app to control Airport Express or an Apple TV from your iPhone and iPod touch. Logitech also offers the Squeezebox family of wireless music products, and there are other good solutions as well.
Choice. It's a good thing.