MQTT is a machine-to-machine (M2M)/”Internet of Things” connectivity protocol. It works like Twitter – you have many sensors which post so main server their info which is streamed and other clients/users can subscribe for sensors of interest out of the whole stream. The advantage is very lightweight protocol and low bandwidth usage.
Another advantage is that the sensors do not need specific IP address to operate, they establish the connection to MQTT server and thus you do not need to specially configure your home network to map ports using NAT etc. You just need internet connection, then the sensors connect to the server and send their info.
Peter Lalov sent us today link to his MQTT implementation for ESP8266-EVB with Lua, the project is open source released under BSD-3 licensee on Github.