The latest version of the Zune software, 4.2, was just released. Not all that much changed, but the update lays the groundwork for some more significant feature additions to Zune software and the Zune HD, most importantly in codec support.
Microsoft is just calling this a "maintenance" update, and there are only a couple actual changes to be seen. Most importantly, the software now supports Xvid, Divx and AVI videos, though it'll have to convert them to play on Zune hardware. However, those videos will be natively supported after another firmware update to the Zune HD, which should come this spring. So there's not much to get excited about quite yet, but it's great to see Microsoft actively supporting the Zune HD like this. [Zune]