We know that ads can be targeted based on the tags a user is browsing. Given the recent promotion by Telerik, we saw that SO also has the ability to target an advertisement to a subset of users based on their metadata, in this case users with 10,000 reputation or more.
Was this a one-off situation, or does SO (and SE) have the ability to target ads to users based on other arbitrary metadata as well? For example, pointing frequent question-askers to tutorial books and media, or showing advertisements for expert-level conferences to people with certain Specialist badges?
Just curious how much of our SO metadata is available to the ad mechanism to attempt to provide us with interesting and relevant advertisements.