Several recent applications (e.g. Shazam) have text and image ads which are handled by Google. I can't seem to find how they did this. Is there some new API that you can use to display ads given some key, similar to how the maps API works? Or is this something that developers individually negotiate?
Specifically I'm interested in Google's ads.
The most popular API for this comes from AdMob, take a look: http://www.admob.com/
There's nothing in the SDK to support this, no. However, if you go to Google's AdSense page there's information on Mobile ads.
Google has recently launched AdSense for Mobile and you could apply to be a part of the beta.
http://www.google.com/ads/mobileapps/developerform.html
Note that you need to apply and the requirements are an app which will generate at least 100,000 page views per day.
This is the program Shazam is using.