You are absolutely correct about the way the controllers talk to the sonos system. The actual sonos controllers (both the one you mention, as well as the newer $349 touchscreen version) talk directly to the sonos zone players. the ipod touch or iphone talk to your home network wifi of course. In my case, I have 5 zones spread throughout my home and thus the sonos controller works immediately everywhere. I also do have a i-touch and the interface is fantastic and the price is certainly nice. there are farther areas in the house that it has problems with and its not "instant" in that I have to quit the current app, go to the sonos app, wait for it to connect, etc etc. however, being a free app i can't complain and i like having my "personal" controller being my touch as well as the "house" controller being the sonos one for other people to use.
I understand these are premium products and I want them really badly, but why don't they lower the price or at the very least offer cheaper alternatives. They are almost the only game in town for this kind of product and they made it bulletproof. But an everyday person can't afford it, not even to just set up 2 rooms! They will lose lots of business to Squeezebox...
The big thing about the Sonos is the mesh. You could get similar(ish) results with air tunes or other products, but the level of control isn't as perfected in anything other then the Sonos (from what I've seen). If anybody has tried out similar items, I'm always open. I'm still undecided as weather to get this for myself....now if they streamed video....watch out apple TV!
the mesh is really solid like you said. being able to play lossless audio files synced perfectly in all 5 of my zones, or a different song in each...or any combination... all the while not taking any computer processor or home wifi bandwidth....brilliant. and ease of use as well. I picked up a 6th zone just recently and i never get over how easy it is. I literally plugged it in the wall and after a button press on my controller and about 15 seconds of updating it was part of my system and playing music for me.