IPhone and Android users may increasingly see ads appear in their phone applications, now that Google is expanding its advertising program for mobile applications.
Google has already been trialing its AdSense for Mobile Applications offering with a very small number of developers including Urbanspoon, Shazam, Sega and Backgrounds.
On Wednesday it announced that the service is now in beta, so more developers can start using it.
It's not open to all application developers though. Android and iPhone developers must have a minimum of 100,000 daily pageviews, offer their applications for free, be ready to implement the program right away and agree to participate for at least three months in order to be considered for the beta.
The program could accept developers who don't meet those criteria in the future, so Google encouraged anyone to apply.
In a short video on Google's blog, Urbanspoon said that the trial of the service has gone well. Urbanspoon, which helps users find restaurants, was looking to include ads that users find helpful, Howard Steinberg, director of business development for the company said.
"What we are looking for again is the ability to target via keywords, via geography and to allow the user to look at the whole application as one and not say, 'Oh, that's an ad, I'm not going to pay attention to it'," he said in the video.
Companies like Google and others including Yahoo, Microsoft and AOL that got started on the Internet or with computer software see a revenue opportunity in mobile phones, as people continue to shift toward using Internet-capable smart phones.
Google also already offers AdSense for developers of mobile Web sites and many other companies also offer mobile advertising services.