They've also rolled out a new mobile app promotion ad template for advertisers to easily create the new App Promotion ads.
The New App promotion ads are like the next version of click-to-download ads  which have existed for several years now.
The new App Promotion Ads are only available if you’ve upgraded to enhanced campaigns. Google recommends that advertisers create new new app promotion ads to replace the older, existing click-to-download ads, in order to take advantage of new built-in, smarter ad-targeting capabilities of the App Promotion Ad.
Both the new ad-creation template and upgraded click-to-download ad format are part of the Enhanced Campaigns roll-out, which should be available to all AdWords accounts by now.
The mobile app market is a huge, fast-growing market with over 700,000 Android and iPhone apps today . In fact, the mobile app industry is believed by some estimates to be a $30 billion market in 2012  – which is an utterly remarkable statistic considering this industry didn’t even exist 5 years ago! Google appears to have noticed this too, and so they’ve rolled out this new App Promotion Ad and mobile app promotion ad template to solve for this common advertising use case.
How to Advertise your Mobile App on Google AdWords
Advertising your mobile app in Google is easier than ever. To create a “App Promotion Ad" ad in your AdWords account, navigate to the “New Ad” button and click on the “App / Digital Content Ad” option, as illustrated below. Please note, this only works for enhanced campaigns .
Next, pick the App Platform, Android or iOS. (Sorry, Microsoft and Blackberry users/developers, your phones are not supported at this time!)
Once you’ve picked the app platform, you can then search for your app in the respective app store (Google Play or iTunes). Type in the name of your app, click “Look up app,” then pick the app that you’re trying to promote.
Next , type out the headline and description for your ad. Google will show you an ad preview to give you an idea of how your app promotion ad will look like on a tablet and on a mobile phone.
As you can see, the new app promotion ad format prominently features your mobile app’s icon, and a green link to the app download page, both of which are sure to drive additional attention to your listing and drive more app installs.
What's New With the App Promotion Ad? How is it Different from the Previous Click to Download Ad? It Just Works
The new app promotion ad format is a huge step forward in ease of use in comparison to the previous way of doing this , and is part of Google’s master plan to make ads smarter and more responsive to user context . When I talked to Surojit Chatterjee  this week, he explained:
Previously there was no easy way to do this. Now you put a URL to iTunes or Google Play, we’ll figure out if it works on tablet or mobile, then we’ll only show the ads to the right people. So, if you have an iPhone app, we’re not going to show that ad to an Android user or on a tablet if it can’t run on a tablet. We’ll automatically figure it out. We also have better ad formatting than before. Most of the App developer use cases seem to be nicely handled.
New Mobile App Ad Extensions, Too!
In addition to the launch of the App Promotion Ad, Google has also released a newly revised version of the Mobile App Extension, which lets app marketers deep link to a specific page within their mobile app, right from the ad.
To create a Mobile App Extension, go to the “Ad Extension” tab, then select “App Extension” as shown in the following screenshot:
For example, a user who already has your app installed can be brought to a specific section inside your mobile app, and could complete a conversion inside your app.
Mobile App Advertising Made Simple
If you’re an app developer, particularly if you’re launching a new app, you need to invest in getting some credibility in terms of a large number of installs and reviews so that everyone looking for your type of app picks your app from the list. Alternatively, if you already have a big number of installs and reviews, you could employ this advertising as a way to get even more reviews and downloads and prevent competing apps from ever having a chance.
In summary, the new app promotion ad format is a simple, powerful, effective way to get people to find and use your mobile app right away. Upgrade to enhanced campaigns so you can start taking advantage of this format as a part of your mobile marketing strategy  now!