We've managed to get wind of an official statement from Valve Software on the release date of Half-Life 2 being pushed back. Here is word that was recieved directly from Doug Lombardi of Valve Software:

The previously announced September 30th release date for Half-Life 2 is being pushed back. We are currently targeting a holiday release, but do not have a specific "in-store" date to share at this time. We will release that information as soon as we have confirmed a new date.

As more information becomes available from Valve we'll have it here for you.