The Zune HD is getting a firmware update that will bring ZviD support to the device. You can also display the XviD content through the dock to your TV. It is unlikely that DivX will make it because of proprietary restrictions. The firmware update will also bring smart DJ features like the computer software.
Let hope they keep coming out with updates to add functionality and features. The Zune HD is still lacking over the iPod Touch and not just in the apps department. The Zune HD still doesn’t have WPA2 support which lots of places use, including the University I work at.