Sonos has updated its iPhone app and iPad app (both free) to enable direct streaming from your iOS devices. With version 3.8.3, your iPad, iPhone and iPod touch can be Sonos sources, much like your music library and web services like Pandora.
The feature is a welcome one and works very well. It would be even better if my new iOS sources showed up in the Sonos Controller software on my Macs so I could play those tracks from anywhere. I'd also love to be able to access my large music collection that Sonos gets from iTunes on any of my iOS devices.