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For the maker of Chrome, Google, advertising is a much more serious business. The company makes billions of dollars in web-based advertising, and it definitely won't be too happy when AdSweep, an ad-blocking extension for Chrome, becomes widely available.
Yes, this extension has been around for a couple of months, but extensions aren't yet officially supported by Chrome and there's no easy way to install it. This will change, as Google has recently opened up an API for third party developers, with plans to start officially supporting extensions soon.