Nginx 1.4 can now do SPDY (draft 2). It’s hiding away in a separate file http://nginx.org/en/docs/http/ngx_http_spdy_module.html
So what is SPDY? In a nutshell, it does multiplexing, prioritization and compression of HTTP/HTTPS requests over a single TCP/IP connection. It also enables the server to push data before requested. These enable a browser or web services client to obtain multiple responses quickly by opening and authenticating a single connection to a web server and then issue multiple requests in parallel (well, whenever it wants, but in any case not requiring additional the completion of one request before the next request and not requiring, though still possible, multiple TCP/IP concurrent connections). For more info on SPDY, see http://www.chromium.org/spdy/spdy-protocol.
There is also an Apache 2.2 module for SPDY (https://code.google.com/p/mod-spdy/). Browser support for SPDY is present in Firefox, Chrome, the default Android web browser, and Opera.
If you have production experience with SPDY, good or bad, we’d like to hear about it! Particularly since SPDY is still relatively new and not yet used everywhere, the more information is published, the better.
edit: official docs are up.