Methods, apparatus, and systems for updating firmware for clustered computing platforms. Firmware provided on each platform is loaded for operating system runtime availability. The firmware update process begins by issuing an update directive that includes firmware update data to a first platform. That platform then interacts with firmware running on other platforms to update the firmware for those platforms, wherein communications between the platforms is enabled via an out-of-band (OOB) communication channel or network. In one embodiment, OOB communications are facilitated by a hidden execution mode known as the System Management Mode (SMM), which has the ability to receive and respond to periodic System Management Interrupts (SMI) and execute corresponding SMI handlers configured to support inter-platform communication in a manner that is transparent to operating systems running on the platforms. The method allows firmware to be updated across multiple platforms, such as server blades, using a single administrative action.