What is causing whirring noise in your 2006 Honda Odyssey?

Does the sound appear to be louder when you are steering? Also, does it seem to happen more often if you are running the heat or air conditioning? If so, there's a good possibility it's the Power Steering pump. I had this on my 2005 Odyssey, and it's a known issue on 2005-2006 models. I was lucky enough to get this replaced under warranty. It made the whole drive SO much quieter and nice.