Bought mine today at Costco in NC
I called my Costco warehouse in Greensboro, NC to see if they had the new 4th Generation 32GB iPod Touch, and the woman on the phone told me that they had 11 in stock. I drove over and didn't see any on display or any of the cardboard merchandise pick up cards, so I went to the merchandise pick-up desk and asked if they had any in-stock and she looked it up and gave me the product ID, to take to a register to purchase it. After purchasing, I returned to merch pick-up and got my new Touch, without a problem.
I recommend asking at Merchandise Pick-Up, if you don't see any on display in the electronics section. Also, the warehouse I visited did not have any iPods on the sales floor, so I didn't have any problems with them wanting to sell older models before releasing the new ones. I assume they just hadn't gotten around to putting them out on display yet, or they know the die-hard fans will ask, since they only had 11 (now 10) in stock. Good luck!
By the way, I didn't ask about the 8GB or 64GB, so I don't know if they had any of those in stock or not.