Google has started using its HTTP-boosting SPDY protocol to speed up almost all SSL web traffic between Chrome browsers and Google's web services. Initial reports are that this is boosting speed by 15%+.

SPDY is an application layer protocol designed to improve the speed of the aging HTTP. The protocol has been available with Chrome since the sixth version of the browser, but at this point, it only kicks into action when the browser is used with Google services and a few other test platforms. At this point, Google services use SPDY exclusively with SSL connections.
SPDY was first supported in Chrome 6. But only recently has Google started using the protocol frequently. Google is now using the protocol about 99 per cent of the time (the other 1% is being used as a control group so they can measure the effectiveness of SPDY).

More info on SPDY is available at http://www.chromium.org/spdy/spdy-proxy