Google says that it will soon roll out the ability for developers to add in-app purchase to Android apps. In fact, TechCrunch reports that the feature was originally set to launch in late 2010, but Google delayed implementation to get more feedback from developers.
The feature will enable the kind of freemium apps that are common for the iPhone and other iOS devices. For instance, you might be able to download a game featuring music like Tap Tap Revenge and pay to purchase additional music tracks. Or you could download a video editor like Splice and pay for additional music, sound effects, transitions, borders, or other video effects.
The service will likely allow developers to accept payments in various forms, including the Google Checkout service and carrier billing where available.
PayPal already launched support for in-app payments from Android apps last year, but Google is talking about building support directly into the operating system, which could provide a much more unified user experience.