Immediately after announcing its first in June, Microsoft started seeking engineers and managers to build the "next generation" of Surface devices. The job listings, which were first spotted by , were posted between June 18 and August 2, and are still visible on the Website.

"The Surface Team focuses on building devices that fully express the Windows vision," several of Microsoft's job say. "... We are currently building the next generation and Surface needs you!"

Another mentions "our next generation Surface," and says that the Surface Team "focuses on lighting up Microsoft experiences with touch first computing." (In other words, don't expect a Surface desktop any time soon, unless a touch screen monitor is involved.) Officially, Microsoft says it hasn't announced anything more than the two tablets revealed in June. When a Microsoft blog post from last week referred to Surface as "," spokesman Frank Shaw that the wording was "literary license" and nothing more.

But it's not surprising that Microsoft would plan for additional Surface devices, especially if the first ones meet the company's sales targets. Microsoft expects to sell at least a "" of the tablets, which would be a respectable number for a first-generation device.

Still, the news isn't likely to sit well with PC makers, who will now have to compete against Microsoft for hardware sales. Though most PC makers have kept quiet about Surface, Acer CEO JT Want told the Financial Times that his company has warned Microsoft to "" about releasing its own tablet.