Just a quick note today: Sonos just started shipping a new software update that adds some new Internet radio options, crossfading between songs, some new language support, new alarm settings, and the ability to use two S5's as a stereo pair. None of the features is critical on its own (though the S5 stereo feature is quite cool; when everything is digital, you can do all sorts of neat things) but Sonos already built the best multi-room component system. I sent back my Sonos review system so I can't test this personally. Sigh.
With the Sonos gone, we've been using Logitech's Squeezebox Boom (OK; needs a better remote, the UI is just "OK," and the Sonos is better for multi-room use). The Squeezebox Touch just showed up, and I'll put that to the test once I get some speakers for it.