The most interesting upcoming Android feature that Google demoed at I/O is a “cloud-to-device” messaging API.

在Froyo众多的新功能中，最让人感到有趣的也许是Google在I/O主题演讲上所展示的“cloud-to-device” messaging API了。

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This pilot uses Cloud to Device Messaging (C2DM) which is part of the Android API to link the Google App Engine server and Android client.

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There's even a publisher API for extending the subscription beyond the walls of Google Play and your Android device.

ENGADGET: Google brings in-app subscriptions to Android Mobile