There is an article[1] about finding out what location at google maps user is looking at, based on observing TLS packets and nothing else.

If task at hand is to match encrypted connection to a smaller number of alternative (say identify accesses to popular place, like gmail/facebook login page, etc), same technique of observing packet size distribution over time should probably work quite reliably, and cgiproxy will do nothing to hide it.

[1] http://www.ioactive.com/pdfs/SSLTrafficAnalysisOnGoogleMaps....