It can be a little bit frustrating having to wait for a new client or member server to go through its initial polling period to receive its approved updates (once a group policy has been applied). To help speed the process along, I have found the following command to be helpful on our server and client builds (XP, 200x):

wuauclt /detectnow

This command will instruct the machine to check the update server for updates immediately. Additionally, you can apply the /resetauthorization switch to the command to force a new WSUS cookie to be created and update the machine's group membership.

Manipulate Automatic Updates Behavior Using Command-line Options

Event ID 31 — WUA Update Download