• by Joe Mandese  @mp_joemandese, November 12, 2007

The rate of online ad spending growth continues to ebb, but continues to outpace that of every other major medium, expanding at 25.3% - or by $1.1 billion - during the third quarter of 2006, according to figures released this morning by the Interactive Advertising Bureau and PricewaterhouseCoopers LLP.

While marketing a slowdown from the third-quarter 2006's 33% rate of growth, online ad spending continues to expand on a sequential basis, with third quarter 2007's ad dollar volume rising nearly 3% over the second quarter of 2007.

The results, published in the IAB Internet Advertising Revenue Report, show that all three quarters in 2007 have set new highs - Q1 at $4.9 billion, Q2 at $5.1 billion, and now Q3 at $5.2 billon. Revenues for the first nine months of 2007 totaled $15.2 billion, up nearly 26% over the $12.1 billion recorded during the first nine months of 2006.

IAB President-CEO Randall Rothenberg attributed the ad dollar expansion to headway made with marketers who are "increasingly" understanding the benefits of interactive advertising.

"Marketers large and small have come to accept digital media as the fulcrum of any marketing strategy," he sated.

Peter Petrusky, director of PWC 's Entertainment, Media & Communications Practice, said that based on the current figures, online ad spending is exceeding a $20 billion "run-rate," and growth continues to be stimulated by the expansion of newer online ad platforms, such as broadband video, rich Internet applications, mobile, and social media. The point of view on the latter's contribution may be the subject of debate, following a speech given this weekend by Publicis Chairman-CEO Maurice Levy, who said the zeal surrounding the advertising potential of social networks may be hyper inflated. Levy called Microsoft's $340 million acquisition of 1% of Facebook, "crazy."