Apple released Thunderbolt Display Firmware Update version 1.1 on Monday, an update to address, “a fan noise issue affecting a small number of Apple Thunderbolt Displays.” The update also includes unspecified stability improvements.
Apple’s Thunderbolt Display(s)
If you have a Thunderbolt Display, you should find the update in Software Update. You can also download it as a standalone installer from the update’s KnowledgeBase article. That version is a 942KB download.