[mbelshe]

That's basically what SPDY is. It has two halves, a framing layer (which is generic), and a definition of how to embed HTTP within that framing layer. In theory, you could use the framing layer for other purposes, but we designed it tailor-made for http.

For the original question - HTTP can only send one request at a time. SPDY can send many all at the same time, avoiding lots of round trips. As a side effect, it sends fewer bytes and packets too. look for the IETF slides for the latest data.