The 2.2 release apparently broke the hacks that allowed users to use the Zune 30 as an external HD for storage and such.

Some folks over at Zunerama have already come up with a work around.

First, it's based on the registry hack from before - (described at this link: http://zunerama.com/forum/index.php?topic=970.0)
The difference with the new firmware is that the registry keys have changed. The new registry keys to be modified are:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Enum\USB\VID_####&PID_####\########-####-####-####-############\Device
Parameters
Modify the same three keys as before, and your Zune will serve as an external drive. A different icon will display in the shell, but you'll have the same functionality.

Source :Zunerama via Crunch Gear