Apple has released Thunderbolt Display Firmware Update (http://support.apple.com/kb/DL1453) for Mac OS X 10.6.8 or higher. It improves the stability of the Apple Thunderbolt Display.
 
The updater application will be installed in the Utilities folder inside the Application folder and will be launched automatically when you close the installer. Apple says to then follow the instructions in the updater application to complete the update process.