In an effort to combine two promising platforms that have yet to pay dividends, Google has begun experimenting with mobile ads for YouTube.

"You may have noticed that we started running a test of display ads on select pages of the YouTube mobile site in the U.S. and Japan. This is our first step in testing mobile advertising for YouTube," Christine Tsai, a YouTube product marketing manager, said on Google's mobile blog on Monday.

According to officials at YouTube, the test will give the company and advertisers valuable insights into how people consume content on their mobile devices.

While mobile advertising has long been plagued by talk of potential, the medium is gaining momentum with the arrival of the iPhone and news that Google has inked a deal with T-Mobile to begin rolling out its mobile platform, Android, next month.