If you open up your Zune desktop software for very long, you’ll be presented with the update to version 2.3. The installation takes about 10 minutes, which includes checking for the update, preparing the computer, and then installing the Zune software.
Apparently, this is a bug update not a feature update. I’m hoping that the performance issues have been resolved.
Or, you can grab the update from the Microsoft download site, if, say, you need to deploy it to multiple desktops.
Microsoft Download location