As you'll be aware, Google and Facebook now force HTTPS on when you talk to their servers, and this privatisation of the data connection between the information mine (you and me) and the information miner (any free web service provider) is almost certainly going to increase as ISPs etc try to parasite off of your personal information flows. This effectively removes Privoxy because the browser when talking to a proxy does CONNECT HTTPS and after that all is encrypted.
Usefully, very new Squids can do a thing called SSL bumping (http://wiki.squid-cache.org/Features/SslBump, and especially http://wiki.squid-cache.org/Features/BumpSslServerFirst\) whereby they will insert themselves as a man in the middle to HTTPS connections. Squid has found implementing this hard, so it seems it would be easier for Privoxy to become able to be an ICAP filter for Squid (http://wiki.squid-cache.org/Features/ICAP) instead of replicating all that machinery.
ICAP is basically a very slight addition to the normal HTTP proxy protocol (see http://tools.ietf.org/html/rfc3507\), so it ought to be fairly easy to add. With ICAP support, one simply inserts Privoxy as an ICAP filter for Squid, and now all HTTPS as well as HTTP connections get privacy filtered, which means we can finally tame Facebook and Google etc.
And lastly, thanks for Privoxy