The System Management Bus (SMBus) was defined by Intel® Corporation in 1995. It was originally used in personal computers and servers for low-speed system management communications. It is more or less a derivative of the I2C bus. The current SMBus specification document is Version 2.
Today the SMBus is being used in a small but growing number of embedded devices and sensors, and its always good to be familiar with obscure protocols.
Examples of contemporary use in embedded systems are to communicate with user flash memory in Altera’s MAX II devices, and to communicate with TAOS Ambient Light Sensors.
Here’s an application note from TAOS called the Bit Banger’s Guide to the SMBus.