Apple's new Thunderbolt Cinema displays just began arriving last Friday, and Apple has been feverishly ensuring they will work properly with existing systems by offering a number of firmware updates for these systems' Thunderbolt connections. Today Apple added to these updates by offering one for the display itself, which according to the updater "improves the stability of the Apple Thunderbolt Display."
Granted, not much information is given about the fixes addressed by this update, but if you own one of the new displays you might as well install the update. The update is a small 923KB download that will be installed in your /Applications/Utilities/ folder. When it is opened the updater will provide instructions as to how to apply the firmware update to your display.
As with any firmware update, be sure to follow these instructions fully to prevent any odd problems from happening. If something does go awry during a firmware update, the device may be rendered useless and need to be replaced. Since the Thunderbolt connection to the display allows for other devices to be connected to it, when you update the firmware you might consider disconnecting any additional Thunderbolt devices so only the display is attached to the system via the Thunderbolt port. If you have more than one Thunderbolt display, then update them sequentially by plugging one in and updating it, then the doing the same for the next.
Make sure the display or displays and your Mac are connected to a reliable power source and are not tampered with at all while the update is being applied. Since this update is for a display device, expect the display to shut off, flicker, or otherwise show odd output during the update process.
The firmware update should be available via Software Update, but can also be downloaded from the Thunderbolt Display Firmware Update Web page.