Google rides the radio waves, from News.com looks at how Google AdSense for radio is now being tested in Detroit, before a planned rollout of the program to all Google advertisers.
Technically, Google's been running radio ads ever since it acquired dMarc Broadcasting in January. It's not like dMarc stopped doing what it was already doing when Google bought it. The real change is that Google is integrating the ability for any existing advertiser to make radio ad purchases on a bid basis.
For more on Google's radio plans, see Googleplex Irvine & "AdSense Audio" For Radio Ads and Speculation: Google To Begin Selling Radio Ads Through AdWords Soon.