The Google-backed Android mobile operating system has received a few high-profile applications that should help it compete better against the iPhone, BlackBerry, and Nokia smartphones.

Facebook made its long-awaited debut in the Android Market Tuesday, filling a significant hole in the platform because competing versions have been available for months in the App Store and the BlackBerry World. The Android version enables users to view their news feed, view their friends' walls, upload photos, add new friends, and interact with the social network in other ways.

The Android version also lets the user add a widget to their home screen that can integrate with the phone's dialer to make quick calls to friends who have their phone number on their Facebook profile. It is missing a few things that are in other versions though, as clicking on a link on a friend's wall will switch to a separate browser. By contrast, the latest iPhone app has an in-app browser so users don't have to exit the program to view friends' links.

The Android app is just the latest sign that Facebook is putting a greater emphasis on mobile access to its site. The social network said it now has about 65 million mobile users, and this could increase substantially over the next few years as it is experiencing growth in many markets where the cell phone is often the primary computing device.

The Linux-based OS also received the popular Internet-radio app Pandora, and the program enables Android users to stream music based on the artist or genre of their choosing. The Android version one-ups the iPhone app by being able to stream music in background, and it also has a home-screen widget for users to give a "thumbs up" or "thumbs down" for any track. The Android version of Pandora is free in the Android Market, but it is only available in the United States.

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