Ballmer vows to challenge Apple, sidesteps phone question - GeekWire

A definite maybe?...

"So what about a Microsoft-developed phone? The company has downplayed that possibility in recent weeks, but Ballmer was more coy in response to the CRN question. From the article …
When asked if Microsoft might make its own smartphone, Ballmer paused and then replied: “Right now we are working real hard on the Surface. That’s the focus. That’s our core. Look, we’ll see what happens. We have good partners with Nokia, [HTC] in the phone space. I love what we’ve got going on with the Surface. We are going to focus on Surface and our other Windows 8 Tablet partners and see if we can go make something happen.”"

Ballmer vows to challenge Apple, sidesteps phone question - GeekWire