Don't you think it'd be cool if you could blog about a party, add it to your calendar and invite all your friends in one fell swoop? After the party, how about viewing photos and videos from the event in the same application? The Google Data APIs make all this possible, and your Google App Engine apps can use feeds from Google services to display and update information for a particular user stored by these services.
The Google Data APIs team just released an update to the Google Data Python client library which includes support for Google App Engine. With this library, your app can now use AuthSub to gain access to your users' feeds.
Jeff Scudder, member of the Google Data APIs team and the main contributor to the Google Data Python client library, has written an article that takes you through all of the steps necessary to use Google Data feeds in your Google App Engine application. He's even added his sample application to our Google App Engine sample code project.
Try out it, and let us know what you come up with!