It's a world, Microsoft says,  where "universal" software applications run across all those devices, where you can plug your Windows phone into a TV and turn it into a PC, where even iPhone and Android applications will run on Windows hardware.

Here at Microsoft Build—the annual developer conference where Microsoft is sharing this vision via a long string of keynote speeches, technology demos, videos, pop music, and shameless hyperbole—the gathered techno-types are applauding the company's new direction. Its effort to rope in software originally built for the iPhone and a world of Android devices, they say, is particularly noteworthy—and particularly necessary, given how far Microsoft trails in the mobile world. "Microsoft has taken a realistic view of its place in the world," says one coder.

But they also question how close Microsoft will come to realizing its ambitious vision. "It makes sense. But it's never going to be as easy as they claim," says Logan McKinley, a developer who builds software for the University of Virginia. "It looks like they've done some cool stuff. But I'm not going to assume it's going to work."