What I'm missing from the article is the server side view. Will it improve server throughput as well? If you have a server that manages 1000 requests/s now, will that be more, less, or equal with SPDY?
Will CPU usage of the server increase dramatically because of compression?
Also, for efficient push methods, the client would have to fill it's cache with server push. That would be a great benefit for sites with many pictures: Initially the first page with all pix is sent, and while the browser displays that page and the user searches for the next link to click, the server could push content in the background. So when the users clicks on the next page, the browser already has most pictures (or other content) and just needs the HTTP page data, resulting in much better browser experience. But there would need to be a server-wide control over that feature, because 200 simultaneous "background pushes" could grind the server to a halt. Could be really nice if used correctly, though.