With a number of deals each hinting at different outcomes, the future of auction-based offline ad-buying is up for grabs, reports Advertising Age.

Clear Channel and Echostar have agreed to use Google's auction system for their radio and cable channels, respectively. On the other hand, numerous financial backers for eBay's trial auction scatter buying system, released in early April, have exited.

It may just be that Google's system is more attractive, waxing assurances for how often an ad will run.

Even so, at least one observer says Google must do more than court new advertisers. It also needs to fully complement in-house operations in a way that does not conflict with local outlets.