Interesting post on Daring Fireball:
http://daringfireball.net/2009/07/chrome_os_context
Summing it up he seems to believe that Chrome OS may be too thin of an OS though he believes that the future is server-side client services. It's also intereting that he notes that while Chrome OS uses web apps similar to the Pre, Android uses native apps.
I think what people are missing here is, "the computer is the network".
The network is a client and a server at it's most basic level and one level up from there the server then handles all the connections on behalf of the client.
Thin machines are just the clients, so as far as the cloud is concerned they are just buckets collecting rain.
The computer may have both server and client in one box so the computer is a network in it's own right, but can hook in other networks with the server handling it all for the user. It is a cloud in it's own right. It might drift into part of another cloud and become part of that cloud. Drift off again taking part of the other cloud with it and join another cloud.
All your data will still be on the server but the server will sync to other servers to clone the data, these clones maybe other devices like your desktop, or your TV, Fridge,Work computer, Company server, Online service. Or syncs maybe split over many and various store houses, gmail, flickr, youTude, googledocs,.....
Your Machine is as much part of the whole network as it is a standalone machine. I think this is what they are referring to when they say it's has been design for the net, unlike the OS's we have now which see themselves as having other functions plus being conduits to the net.
As part of the net the machine will seem no different online or offline. It could go as far pooling pushed content so it there for you regardless of network connection. It could be able to build on the fly networks with other devices. The internet stops being somewhere else.
Or it could be a thin device that is just another bucket under a cloud then they are right it is too thin.