I don't see this as more than a gimmick (a nice one, sure). You end up with mute, non-semantic icon names (single characters) in your CSS, single-color icons on

I don't see this as more than a gimmick (a nice one, sure). You end up with mute, non-semantic icon names (single characters) in your CSS, single-color icons only. Vector graphics are nice, but then you might as well go for SVG. The one valid use case for this is limiting the number of roundtrips & requests. But in the long term, there'll be SPDY (or some other similar protocol) for that. And SPDY fixes the problem for your whole app / page, not just icons.