Owen Thomas of Valleywag picked up on something interesting regarding Google’s new contextual ad technology. Essentially, Google is leveraging user privacy concerns as a means to acquire more information about users.

Let me explain. On Wednesday, Google announced via the Google Blog new “interest based” ads that associate users with certain categories, all to display tailored ads that are more relevant. Basically, if a user browses multiple running blogs, the next time the user goes to, say, Amazon’s sporting goods section, Google will know to display ads about running shoes instead of any run-of-the-mill sportswear.

Make sense? Google is essentially tracking users browsing habits via modified cookies stored on the browser in order to serve up the most relevant ad possible.

Of course, knowing that the privacy alarmists will cry foul, Google makes it extremely easy to opt out of the program. Google is also kind enough to let users see which categories they are aligned with based on their browsing habits and delete any the user feels are irrelevant.

This is where Owen Thomas spots shenanigans:

Google is making it easy to modify the interest information Google stores. You can opt out, but then the "ads will be less relevant to you." (The horror!) What Ghosemajumder, Wojcicki and the rest of the Googlers are really hoping you'll do is add or subtract interests to the list rather than opt out — and thereby give Google even more information about you.

The ads are still in the beta stage, meaning Google may still tweak or scrap the program. But what do you think? Are you concerned about what Google is doing here? Do you really need ads that are more relevant? Do even click on Google ads anyway?