From reading complaints about AT&T and the iPhone from people in/near San Francisco, I'd say a mobile phone running off a flaky 3G network is a common issue inside of Silicon Valley.

That said, Sproutcore lets you build rich applications that happen to run inside of a browser. If an app's requirements include "Mac OS X 10.5 or later," then I need to run on it on a Mac. Civilization V requires a discrete graphics card; I won't have much luck running it on a Netbook. And, Sproutcore apps require Javascript.