You may have seen that ARM has been developing some low level trusted firmware to provide reference code that supports Secure World software on the latest v8A technology based chips. The software is available here on GitHub
ARM-software/arm-trusted-firmware · GitHub
Rod Crawford posted the links to a video introduction by Andrew Thoelke on the project and its background at Linaro Connect
ARM Trusted Firmware Open Source Project at Linaro Connect
Since v8A based development platforms are at an early stage it is difficult for most developers to get access to hardware. So how has ARM managed to develop the trusted firmware ahead of silicon? The answer has been to use the v8A Architectural models which include support for Secure World. These models are low cost and available now - as ARM part number "EM008 FL". The combination of the v8A Architectural model and the Trusted Firmware on GitHub provide a good starting point for developing secure world software on the next generation v8A based platforms, even before hardware is in your hands.