The WSJ has a report (registration required) on digital marketing agencies beginning to take the lead over traditional agencies in larger not-necessarily-digital campaigns:
Even as Internet advertising has been growing rapidly, marketers tend to confine the agencies that design their Web and email ads to online work only. They hire other agencies to create traditional ads, known as "above the line work" in industry terminology. Sometimes traditional agencies take a shot at designing Web ads, but the assignments rarely go in the opposite direction. That usually ensures that Web agencies have little clout when it comes to big campaigns, which often are dominated by TV spots or glossy magazine ads.
Of course, this is changing and digital shops have the advantage because most media are becoming digital. In addition to digital fluency, they have an automatic leg up by not being wedded to aging creative, buying and planning processes, particularly around television and print. They also are more fluent in customized, niche marketing, and generally are more nimble and able to follow splintering consumer attention.