From a product-design perspective, the notion of putting the Windows Phone interface on slate-style computers seems like a no-brainer as Microsoft looks to compete with the iPad -- as we demonstrated with a few simple mockups earlier this year. And increasingly, Microsoft CEO Steve Ballmer is sounding like he's on board with the concept.

In a wide-ranging new interview, Ars Technica's Peter Bright asks Ballmer about the future of Windows tablets. Ballmer responds, in part, that "you'll see some stuff now, you'll see some stuff after Christmas, you'll see some stuff as we get new Intel chips, you'll see some things as you move Windows Phone along."

That's notable because Ballmer has said repeatedly that Windows is Microsoft's operating system for slate-style devices. But during an interview on stage at the Gartner Symposium last month, Ballmer made it clear that he's not excluding Windows Phone from that definition when he makes those statements.

Holding up a Windows Phone, he said, "This is Windows, too."

The question is whether Microsoft would shift away from its traditional Windows operating system -- and its large Windows profit margins -- on a type of device that the company has long classified as a PC. Reading between the lines, one theory is that the company will offer a special Windows Phone-style interface for slates as an option on top of the Windows operating system, trying to have the best of both worlds.

If that's the case, the question is whether PC makers will view some sort of Windows/Windows Phone combination as a workable and cost-effective choice for slate-style machines, or go with an alternative.

Which is why it will be particularly interesting to watch how the emerging crop of Android slates is received.