Andy created the Lua library as part of his work on the Aiko platform, a way of joining up the Internet of Things being created thanks to Open Source hardware like Arduino and the ability to run Linux on platforms like OpenWRT. He also notes that it will run on a Playstation Portable! In theory it should also be possible to run on other platforms that support Lua scripting such as Android using the Android Scripting Layer (although some work might be needed to add the library to the SL4A environment).
The Software page now lists the client APIs in alphabetical order of language implementation, with the exception of the 2 device-specific implementations for Arduino and mbed. As the note at the top of the section says…
… not all of the client APIs … are current. Some are at an early or experimental stage of development, whilst others are stable and mature … some may not provide full support for all of the features of the latest MQTT specification.
It continues to be great to see developers working with the protocol and providing their APIs for others in the community to use. We’re happy to list them here on mqtt.org, so please let us know if you are working on anything that should be shared. Thanks for your contributions!