The Chromecast is getting a new update to build 13300. It is described primarily as a "maintenance update" and doesn't really add any new features. Here's a quote with the details,
The Chromecast device has been updated to build 13300. This update will be rolled out over the next week, and you should receive the update automatically. The update is largely a maintenance release, and contains the following changes:
More information about the Chromecast device is available on the Chromecast site.
- Kernel update
- Security fixes
- Robustness improvements
- Security enhancements
Roshan Baliga
Google Chromecast
Source: Google Chrome Releases Blog via GoogleTVForum.org