Just wait it appears, the date must be launched for this application. In-app billing is an Android Market service that lets you sell digital content in your applications. When you use the Android Market In-app Billing service to sell an item, Android Market handles all checkout details so your application never has to directly process any financial transactions.
Also, the transaction fee for in-app purchases is the same as the transaction fee for application purchases (30%).
Any application that you publish through Android Market can implement in-app billing.
To help you integrate in-app billing into your application, the Android SDK provides a sample application that demonstrates a simple implementation of in-app billing.