We've managed to get an official statement from Valve Software on the release date of Half-Life 2 being pushed back. Here is word that I got directly from Doug Lombardi of Valve Software. Valve seems to have been having some mail issues so you may not see this on other sites, however we can confirm with absolute certainty that this is valid:
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.
Steve Gibson is the cofounder of Shacknews.com. Originally known as sCary's Quakeholio back in 1996, Steve is now President of Gearbox Publishing after selling Shacknews to GameFly in 2009.