Obviously, Time Machine is a very complex and ground-breaking application. Unfortunately, it looks like Apple wasn't able to get it completely running the way it would like in time to get out the door. It does really great work to a local USB or Firwiredisk. However, you won't be able to back up to Network Drives at all whereas you (in the Leopard Betas) were able to back up to Airport Extreme USB disks as well as other SMB and AFP shares. A@ron at Macrumors forums was able to revitalize this functionality by doing the following:
1) disconnect airport disk and plug into computer as a USB drive directly.
2) Set up time machine to use this volume.
