I've noticed that there are a good number of sites (Google, Twitter, [Wikipedia](https://security.stackexchange.com/questions/20660/what-is-the-impetus-for-major-sites-being-https-exclusive-now#comment34129_20660)) that are serving up every page over [HTTPS](http://en.wikipedia.org/wiki/HTTP_Secure).

I can understand given that everyone is concerned over privacy now, but has there been some sort of best practice/impetus for this change?

Perhaps it's one of those things that it's just easier to use, because you get certain guarantees out-of-the-box?

It's been explained to me that it could be because of privacy concerns that were emphasized when the [Firesheep Firefox plugin](http://codebutler.com/firesheep/) was released at Toorcon 12, but that was two years ago, and I seem to recall major sites making the switch to HTTPS-exclusive more recently.