Google’s Chromecast dongle is only about a week old but it is already getting its first OTA update. The maintenance release will deliver a variety of unspecified improvements but does not add any new functionality. According to Ambarish Kenghe, Chromecast Product Manager:
Today, we are pushing a bug fix update to Chromecast devices to improve performance, reliability and security. The update will roll out over the next few days and will happen automatically; users do not need to take any action.
The update will not require any user intervention and will done automatically over the next few days. Once completed, the Chromecast software version number should jump from the current 12078 to 12840.
The Chromecast is only available in the U.S. at this point where it had a strong debut. Google is expected to widen availability to other countries but it has not given any timelines for when it will do so.
Sources : Google Chrome Releases // Phandroid