Yes, because the URI is also encrypted in HTTPS (although it can get leaked in other ways; see the discussion at http://stackoverflow.com/questions/499591/are-https-urls-enc...).

But the host is not, and many services exist to categorize the content of domains already. What is the statistical difference between innocuous-site-with-every-kind-of-content-ever.com/friendship-is-pornographic and mlp-fip.com? If more sites are like the latter, then HTTPS will only hide which MLP pictures you are looking at, and not that you are looking at MLP porn. And if a site like the former became too large, we'd have to worry about the government issuing secret trace/tap requests against them.

That thread misses the most important way: the length of the request and the length of the response. On most small sites, the combination of the two will be enough to uniquely identify what page you're visiting.