1) actually, to my understanding it's a pretty common practice. i know that i at least have been served ads based on queries i just made, or pages that i just visited. i'd be very surprised if i was the only one here on HN who has had that experience.
2) that's certainly true, but i'd say that means we should be concerned about those alternate methods as well, not that we shouldn't be concerned about this one.
1. I don't doubt that google (who owns 60% of ad space online) doesn't have some kind of profiling on you already, but they don't need http referers to build that data. Hell, even the example email in the blog has nothing to do with referer tracking, unless gabriel is suggesting that wikipedia is running hidden ad trackers on their pages.
well, i think Gabriel's point (though he's had some trouble getting it across) is not that Google is building the profile on you, but rather that other ad networks are.
you do raise an excellent point about the email example, though. hopefully Gabriel or Matt could shed some light on that?
2) that's certainly true, but i'd say that means we should be concerned about those alternate methods as well, not that we shouldn't be concerned about this one.