First, check that you have the latest version of Zune on your computer. To verify that, open Zune, click Settings at the top of the screen, then Software > General > Check for updates.
On your phone, verify that the update notification is enabled. Navigate to Settings > System > Phone update. Check both boxes on that screen.
Connect your phone to your computer and restart. Try again later if, like me, you do not see the update notification.
Anyone got the update yet?