The company denies recent reports that it's working on a "ZunePhone" for Verizon Wireless, and it will focus on upcoming Windows Mobile upgrades. Despite the latest round of whisperings, Microsoft is insisting it will not be making its own smartphone. It's not the first or the last time the software vendor has been at the center of speculation when it comes to backing its own breed of iPhone or BlackBerry. Whereas Windows Mobile competes with the likes of Research In Motion and Apple in building operating systems, Microsoft's rivals have control over nearly every aspect of their smartphones. That's because they produce the hardware. Microsoft merely licenses its mobile OS to partners to build smartphones. But there have been rumblings that the software maker is interested in creating its own smartphone to give Verizon Wireless a significant rival to the iPhone. This device reportedly could have been built by Sidekick maker Danger, which was acquired by Microso