The other unifying factor for tablets, phones, PCs and gaming consoles are Web-based cloud services, Belfiore said. Microsoft is building its own cloud offerings through services such as Windows Live, but also trying to integrate social networking tools that people most care about, such as Facebook and Twitter.
"What we're trying to do is use the cloud as a mechanism to aggregate all the things that you would care about on the back-end and get them to those screens in a right, meaningful, well-designed way."
The company announced smartphones from HTC and Samsung running on Windows Phone 7.5. The smartphones available from AT&T include the US$199.99 Samsung Focus S, which has a 4.3-inch screen; the $49.99 Samsung Focus Flash, which has a 3.7-inch screen; and the HTC Titan, which has a 4.7-inch screen. HTC's Radar 4G has a 3.8-inch screen and is available on T-Mobile's network for $99.99.
Company officials declined to comment on when Nokia's Lumia smartphones, which also run Windows Phone, will be available in the U.S.
The Windows Phone 7.5 software will be provided as a free software upgrade to existing Windows Phone customers.
Sign up for CIO Asia eNewsletters.