SPDY: An experimental protocol for a faster web
SPDY is a google initiative to make serving web pages faster by fixing some of the flaws in HTTP. It adds a layer on top of TCP that allows several streams over one connection. HTTP then goes on top of it.
Their experiments show a performance boost of up to 50%
SPDY has been enabled in Chrome since Jan. 2011. Since it requires the server to be SPDY aware also, it only impacts when chrome connects to google's servers.