Google and Yahoo! are both making their paid-search advertisers' online campaigns available in mobile search results, at least on smartphones. As a general matter this simplifies the process for advertisers, who can make one ad buy and get distribution across platforms. That's not truly been possible for display advertising to date (unless you count Google's content network's automated banner creation from text ads).

However in a move that will have significant implications for online ad networks and potentially display advertising as a whole, mobile ad exchange Mobclix has announced a deal this morning with AOL's Advertising.com and Trafffic Marketplace. The deal will facilitate cross-platform display ad buying. The idea is that the two online networks now become a place that advertisers can buy mobile display inventory, as well as online, via Mobclix. 

Mobclix says that it's the largest mobile ad exchange and works with more than 20 leading mobile ad networks. Mobclix's rise has been very rapid. Founded in September, 2008 the company promises "100% fill rates" for publishers and app developers. 

As mobile gains momentum -- Jumptap told me last Friday that it has seen a big increase in RFPs from advertisers in the past few months -- this sort of cross-platform capability becomes highly desirable and will help accelerate that momentum. It creates a kind of "instant reach" to mobile audiences.

One of the historical inhibitors of mobile ad buying for agencies and large advertisers has been the fragmentation of the market. This deal (and others that will likely emulate it in the future) overcome the problem of fragmentation by creating a "one-stop-shop" opportunity.  AOL's Third Screen Media was part of its former "Platform A" initiative that was supposed to be that sort of "one-stop shop" for display ad buying; however the promise of that concept was never truly fulfilled.

Recently AdMob acquired ad "mediator"/exchange AdWhirl. Arguably the most visible mobile ad network, this announcement may put some pressure on that company and other mobile ad networks to make similar cross-platform deals. Accordingly we're probably entering a time of increased deal-making and even consolidation in the mobile ad network space as the economy improves.