Ad buyers who purchase Google text ads will soon start seeing their ads show up on mobile devices in addition to the Web.

According to the blog Search Engine Watch, the integration will start within the next few days and be free to users through Nov. 19.

The integration involves Google AdWords, the company’s service for delivering targeted text ads against search engine results. Beginning shortly, those ads will be delivered on both the Google Web search engine and Google Mobile Search results. Google will only serve ads to mobile searchers when the landing pages for those ads are optimized for, or can be viewed on, a target mobile device.

According to the report, integrated delivery to the Web and mobile search listings will be the new default setting within Google AdWords. Users will be able, however, to opt out of having their ads delivered to mobile devices.

That distinction will undoubtedly result in some bumps in the road for Google and its advertisers. Ads on the Web and mobile devices are likely to chase different goals, aim for different types of users and use different technologies on their landing pages. The decision to integrate the two media, however, will give a boost to the mobile advertising market, instantly moving a large inventory of ads that will now run against Google Mobile Search results.

Google has been circling the mobile space lately as rumors of an upcoming Gphone have been ramping up of late. Mobile AdWords will undoubtedly be a major component of any Google phone—and could be the engine to keep the phone and mobile services cheap or even free.

Google is also expanding its AdWords and AdSense text ad programs, most recently experimenting with a new ad format that would run them as an overlay on video programming.