It's not a major dashboard update, but Microsoft has officially added a previously removed feature to the non-gaming console, and promises that a few more tweaks are still incoming. This particular dashboard update, while bringing back to the "Boot-to-Disc" option, is meant for one thing, and one thing only: to stop pirates from using the Xbox 360 console. And, if forum members are any indicator, it looks like Microsoft has been successful so far.
The update is officially known as the "Anti-PIracy 2.5 update." The update removes the option for owners of a flashed Xbox 360 firmware to load bootleg titles on their console. The update itself is mandatory if you want to play on Xbox LIVE. The update does indeed bring back "Boot-to-Disc," which was a feature that was removed in a previous update to try and stop illegal usage of bootleg games.
As for those subtle tweaks, Major Nelson says that the GamerCards that players use will be changed. You won't be able to see which "Gamer Zone" another player is in, and the cards will be taking a darker shade. The changes to the gamer cards will be implemented on January 20th. You can see a video below of the new dashboard update in action.