Seems that there are wide reports that traffic driven by Google on a constant basis have suddenly and dramatically dropped since September 22nd and 23rd. Forum reports at WebmasterWorld account for many people who have seen a significant loss in the traffic delivered to them by way of Google.
Here are some quotes from the thread: - Traffic dropped from 2000 to 350 - We have been getting about 2000 hits per day for the last 1.5 year. Sept 23 hits are down to about 350-400. - Yep, me too! 4500 to 700.