It turns out that the report of the Zune Software coming to the Mac is not true according to this blog posting. There will be an Apple Mac application that will sync media from the Mac iTunes Library to the Windows Phone 7 device, but not to a standard Zune Media device.
So, it seems that Microsoft is still keeping their Zune devices segregated to the Microsoft PC world, but opening up their Phone 7 devices to the Mac platform.
UPDATE: I just downloaded and tested the Windows Phone 7 Connector app for the Mac, and it does indeed NOT work with a standard Zune HD device. It will only work with a true Windows Phone 7 unit.