Mozilla has already made available a Firefox OS Simulator to run from your web-browser and Firefox OS is available for tinkering with your own hardware, but now you can get a Firefox OS Developer Preview device.
This developer phone is being made by Geeksphone and Telefonica. The hardware for this developer/preview phone isn't too exciting. The phone comes down to a 1GHz Qualcomm Snapdragon S1, UMTS+GSM connectivity, 3.5-inch HVGA Multi-touch, 3 Megapixel Camera, 4GB ROM, 512MB RAM, MicroSD, and 1580 mAh battery. About the only desirable feature with this hardware is that the phone is fully unlocked. There's two phone models to be launched beginning next month with fairly similar specifications. Unfortunately, no pricing information has been revealed, but will likely come at a premium.