Several developers released new Facebook-integrated mobile web apps today to coincide with the launch of Facebook’s mobile application platform. The Huffington Post, Flixster, AudioVroom and others provide an early showcase of the potential of the platform, including the ability to integrate with a mobile device’s GPS, media player, audio output, and more.

While less full-featured than Facebook web apps and slower than native smartphone apps, these third-party Facebook mobile platform apps demonstrate how lightweight experiences built on top of the social graph can provide utility.

Here’s how four of the utility app mobile platform launch partners are integrating social and native phone features into their mobile Facebook apps:

HuffPost for Facebook- The Huffington Post’s news reader mobile web app shows a iOS hardware access request to “use your current location”, which allows it surface local news from its Patch network in a “Nearby” tab. This feature will make it especially useful those who want to learn about their surroundings without visiting a dedicated local news site. By pulling a user’s interests and friends, HuffPost can also provide  recommendations of articles that friends are reading, Liking, commenting on, or that relate to one’s Likes.

Flixster – This movie reviews Facebook mobile app lets users select to watch film trailers which are instantly opened in the iPhone’s QuickTime player. The app makes it easy to find out what’s in theaters, watch trailers to determine what to see, and then share plans with friends. Flixster also has a native iPhone app so in some cases it will launch that app if installed or open the App Store to download it.

BranchOut – The Facebook canvas app for professional networking now also has a mobile platform version. Streamlined to promote real-time activity, the app defaults to its status update publisher that lets users post simple text updates with those they’ve established BranchOut connections to. This differs significantly from the web app which starts by showing users job opportunities and other more complex options.

AudioVroom- This mobile music app creates a streaming radio station based on a user’s Facebook Likes. Music is output directly through a mobile device’s speakers or headphone jack. For those who want mobile streaming radio but don’t want to spend time teaching Pandora their preferences may enjoy AudioVroom.

Facebook doesn’t yet allow mobile apps to integrate with the Open Graph. It says it will soon, though, so mobile platform apps will then be able to publish activity to the Timeline and Ticker in order to attract new users.

It will take time for developers to realize the true strengths of Facebook’s mobile platform and see what resonates with users in this new medium. It will need polish in the form of tools and documentation if Facebook wants developers to choose it instead of or as a complement to building native apps for iOS or Android.

If Facebook can help guide its launch partners to create unique experiences that show off its deep ties with the social graph, it could convince more utility app developers to experiment with its mobile platform.