In keeping with its policy of same-day releases when new device operating systems are available, Xamarin has released a new version of Xamarin.Mobile that is compatible with Windows Phone 8. It has also announced a developer contest.

Xamarin.Mobile is a library that exposes a single set of APIs for accessing common mobile device functionality across iOS, Android, and Windows platforms. It complements Xamarin's Mono products, Mono Touch for iOS and Mono for Android.

Xamarin’s cross-platform mobile development software, which was initially launched in November 2011 and is currently in a preview release, allows developers to build native iOS and Android apps using C#, which means these apps can also share code with apps on Microsoft’s mobile platforms.

It enhances code-sharing across device platforms by providing a single API for common device services like contacts, camera, and geolocation. Instead of writing unique code for each platform to leverage the camera API, developers can code to a single Xamarin.Mobile camera API that will work for iOS, Android, Windows 8 and Windows Phone 8.

Simultaneous with the launch, Xamarin is also announcing its first ever developer contest, the Xamarin Developer Showdown for the best iOS, Android, Windows 8 or Windows Phone 8 app that uses the Xamarin.Mobile library.

Apps will be judged based on the quality of the native user experience and the best use of Xamarin.Mobile. Winners for each target platform will receive a choice of an iPad, a Nexus 10 or a Microsoft Surface tablet. The overall grand-prize winner will receive all three tablets.

As there are no cash prizes involved there are no eligibility restrictions and the rules are simple and to the point:

• Pick your piece: iOS, Android, or Windows
• Build a working application that uses Xamarin.Mobile
• Submit the application to Xamarin for review
• Produce and submit a short video that demonstrates your app

The deadline is November 30.