Google buys DoubleClick, the ad-serving company, for $3.1 billion dollars.

“The most compelling argument (for the deal) is it is accelerating our display advertising business,” Google Chief Executive Eric Schmidt said“

This purchase, if it goes through, means that Google would account for 80 percent of the ads served up on the Internet, according to this source. Yahoo, Microsoft, and AT&T are encouraging regulators to take a close look at Google’s planned purchase.

Meanwhile, Robert Scoble is wondering if Microsoft are bidding up acquisitions on purpose? Are Google building moats around their lucrative paid text link selling (grin) business?