My initial reaction before I had known this was to wonder why Google was trying to create an alternative to HTTP referrer header? [rhetorical question] Then after reading about the strong suggestion from the IETF I tested this theory out by creating a test link on a site served as HTTPS and my site's log showed no referrer was set.
I have seen 'http://www.google.com/' in some referrers of late, not cool at all. This doesn't tell me what my visitors from Google are looking for and in turn I can not improve my site's content. I do improve my site's content and in example wrote a new blog entry about the longevity of AMD's socket FM1 since a lot of people were interested in that based on the referrer data in my visitors log. However I would bet all the gold in the world my PR 4 personal website does not have a link to it sitting on the Google homepage (though I would love to be very very wrong about that).
If Google plans on sending referrer data to webmasters and try to "protect privacy" of their users at the same time then they sure had me fooled! In the most ideal situation for everyone someone at Google severally goofed and failed to realize you address technically competent people first without fail, privacy advocates who aren't technically competent come second to those who are technically capable and yes, many of us who are technically competent do advocate for privacy. However that's a very very optimistic hope for a company that has proclaimed that they would drop support for the license and patent encumbered H.264 codec backed up likes of Hollywood, the RIAA and MPAA.
So until Google makes good on fully restoring referrer headers I'll be sticking with Bing and Yandex and advocating to everyone I know not to use Google.