We went to our usual Walmart today and at the checkout I swiped my Penfed CHIP & PIN card as usual and the clerk said, "it looks like you have a CHIP card, you need to push it into the slot at the bottom". I did so and after reading my card up popped the usual signature box. So, I know that the CHIP works, and that our Walmart has now upgraded to CHIP & Signature and insists on using the CHIP for authorization even though the card still has a magnetic stripe which I've used everywhere else to date.
I guess I'll find out in 10 days or so if the PIN works when we go to Canada.
All in all it was a successful morning as we stopped into Walmart on the way back from the airport having had our interviews for the Global Entry / Trusted Traveler program. The emails confirming our approval were waiting for us when got home. Something else to try out on our upcoming flights