The update applies to MacBook Pros built in mid-2012 and "some" Thunderbolt cables, however it is not clear if all cables are affected, or just those made by Apple.
From the release notes:
About Thunderbolt Firmware Update v1.1
This update addresses an issue with MacBook Pro (mid 2012) and some Thunderbolt cables that may prevent bus-powered Thunderbolt devices from functioning properly.
Thunderbolt Firmware Update v.1.1 comes in at 442KB and requires OS X Lion 10.7.4 or later. It can be downloaded through Software Update or Apple's dedicated support downloads webpage.