Switched On: Surface tension
If you hadn't been paying too much attention to the wide swath of tablets and clamshells (and mashups of the two) that Microsoft is targeting with Windows 8 and Windows RT, then the announcement of Surface contained many surprises. If you have, then there were probably far fewer surprises. But even if you knew just about everything about Windows 8 and Windows RT, you were probably a bit surprised to see Microsoft jump in with its own pair of devices to support the flavors of the imminent Windows upgrades supporting Intel and ARM processors.
After all, the fundamental business model of Windows has relied upon licensing to third parties. Ballmer himself has noted in the past that products that ship in the hundreds of millions (or more) of units per year lend themselves well to the licensing model as opposed to the vertical integration model most notably pursued by Apple among Microsoft's main competitors.