Over in Redmond yesterday I arranged to stop by Microsoft's new Retail Experience Center, which probably would have been named the "Store of the Future," except the company hopes to see many of the concepts implemented in the short run. There were lots of interesting tech prototypes, such as shopping carts that use RFID to display information about nearby products as someone walks through the store.

But the funniest part was the Apple joke.

To set the scene, the pretend store is filled with Microsoft brands. Glowing Windows logos greet visitors after they walk through the realistic front doors. On the store floor are futuristic displays for Zune, Xbox 360 and Windows-based PCs. Windows 7 powers a flat-panel, touch screen store guide that offers personalized discounts and information after a shopper scans a loyalty card.

Microsoft Surface is used for product comparisons. Microsoft's IT management tools allow the computers on the floor to be automatically updated with new content and software updates. In the back room, the fictitious store manager can fire up Microsoft business applications to get the latest sales data. And so on.

So I was surprised to see a bunch of Apple boxes and packaging on a shelf on one side of the store. I was surprised, that is, until I realized which section of the store we were in.

It was the returns department.

"It's a little inside joke," explained one of my Microsoft hosts, with a grin.

No doubt it provides a moment of levity on the standard tour. The boxes aren't evident in Microsoft's stock images or Photosynth gallery. I would have snapped a picture, but Microsoft is taking a secretive approach to the prototype store, not allowing outsiders to shoot photos or video out of concern that its competitors might see something it doesn't want them to see.

That didn't make sense to me at first, either, because the idea behind the store is to develop and share concepts with the retail industry. What's to hide? When I asked that question, Microsoft's Stephen Sparrow acknowledged that the company doesn't want to inadvertently give Apple any big ideas for its stores.

However, Sparrow said, the prototype Microsoft store isn't a prelude to a real Microsoft store. He acknowledged some of the speculation to that effect, but he said the facility was created purely for the benefit of retailers, packaged goods companies, hardware makers and other Microsoft partners.

The 20,000-square-foot facility, inside an unmarked building in a nondescript Redmond corporate park, has been there since June. Microsoft has been touring customers through it since August, and Microsoft announced its existence at the National Retail Federation conference this week.