With a recent update, Google put all its searches on SSL (https), officially for security reasons; the outcome is that in Google Analytics it won’t be possible to see what queries are leading traffic to our website anymore: every search will increase the rate of “not provided”
It might be a security reason, but surely it makes more important the use of Adwords, not only as a paid traffic platform, but also as a SEO testing tool.
(resource in italian here)
SEO CAFE' - blog di andrea sardo 