WSUS
WSUS is now available. Documentation includes:

Step-by-Step Guide to Getting Started
...with Microsoft Windows Server Update Services. More...
...on Windows 2000 Server. More...
...on Windows 2003 Server. More...

Also the Microsoft Windows Server Update Services Operations Guide. More...

There's a WSUS Deployment webcast available. More...

Finally worth noting is an MVP's site on WSUS.