For the first time ever, Nike has made available an API that lets developers build apps that work with its fitness offerings. While the API is only available in a limited beta for developers participating in a hackathon at the SXSWi event in Austin, Texas, this week, the move is likely to lead to wider availability in the near future.

According to a report over at TechCrunch, Nike made the API available to hackers participating in a music-related hackathon hosted by Backplane. Nike is helping developers create music apps that work with its new, wrist-worn fitness device, Nike FuelBand. The device is a competitor to Jawbone's UP, Fitbit, Basis Band, and many more (here's a roundup of 10 similar offerings).

The device’s name, Nike+ Fuel Band, comes from the virtual health currency, or the composite score, that the device tracks: Nike Fuel. The Nike+ Fuel Band leverages just two sensors: the standard 3 axis accelerometer, which monitors activity, and an ambient light sensor that detects light levels in the user’s environment and automatically adjusts the brightness of the device’s display accordingly. The device’s display is made up of 100 white LED lights that show the time, Nike Fuel earned, calories burned, and steps taken. The wrist-worn device only has one button. When pushed it scrolls through the various metrics the device tracks. Holding the button down brings up advance features, like Airplane Mode. The side of the device has 20 colored LED lights (green, yellow, red) that give users a quick reference point for current performance levels. Users can transmit the data from the device to an iPhone running iOS 4 or 5 via Bluetooth or through a USB cable that plugs into the user’s PC.

More on the beta launch of the Nike Fuel Band API over at TechCrunch