Windows 8 will hit general availability on 26th October and we will see a surge in the applications downloads from the Windows Store for Windows 8 which will feature a number of Modern UI based applications.
Advertising is an important aspect of revenue generation for the developers,especially when they are making the app availale as a Freeware for the consumers.Recently Microsoft detailed the scenarios of Windows 8 in App advertising,to give the users an idea about how they will see the advertise in an interactive manner in their Windows 8 apps.
Take the UP ad for example,the Advertise which is featured in the NBC news application of Modern UI.Delta Airlines which is launching new ad Campaign “UP” thats all about uping the ante of traveling with their airlines.So when the user is in the NBC app,user can touch on the advertise to expand the ad tile!user can also swipe up the advertise to continue the visual journey of travel experience—from checking in at the airport, to bags going up the ramp, until the plane is up in the sky—that is simple and aspirational.After the experience is closed, users are returned to the NBC News app content.Agency partner for this Delta campaign is Razorfish.
Another interesting in app advertising campaign is from Papperidge Farm,Who are looking to expand their reach to the teens.Y&R Group who are handling this campaign has come up with a great idea for this advertising in Slacker Radio.This Concept allows users to stay tuned to the app and enjoy the branded experience without leaving the app.They have created a “Music Visualizer” with GoldFish Crackers,so the GoldFish Crackers jump and dance to virtually any track which you are playing on the Slacker Radio app 
You can checkout the Video which features the concepts in Windows 8 in app advertising.
Source[Microsoft Advertising Blog]