Once that's in place, everything else is just business model, Rubin says.
The big picture
We've dissected all the main ways that Microsoft is (and isn't) creating a unified experience across Windows 8 and Windows Phone 8, from the interface to personal documents, media, and apps. But there is a bigger picture to keep in mind.
A Microsoft Account (formerly Live ID) now acts as a master key. It connects to SkyDrive, Xbox entertainment, and Microsoft's app stores, but it also ties in to other online accounts, such as Facebook, Google, LinkedIn, and Twitter.
All of these services then become integrated with Windows 8 and Windows Phone 8. You can view your Facebook photos in the People app (which Microsoft calls a complete, cloud-powered address book for Windows 8) or upload them to other apps. People you follow on LinkedIn and Twitter appear in your contacts list. A connected Google account can sync your contacts, calendars, and Gmail.
No other platform is as well integrated with other online services. Even Apple's iOS, which now has Facebook integration, won't let you grab photos from the social network as if it were just another album in your camera roll.
Once you've connected all those accounts through a Microsoft ID, they'll be tied to any Windows 8 tablet or Windows Phone 8 handset you buy in the future, along with Microsoft's own services. No extra work is required to get everything in sync.
When you sign in to either of these devices, they both light up with all your services, Microsoft's Dharmesh Mehta says.
Think of it this way: In the past, you could use Windows without ever creating a Microsoft ID, and be perfectly happy.
With Windows 8 and Windows Phone 8, you'd lose a huge chunk of the experience without a login, because that's where the unification of the two platforms becomes more than skin deep.
Of course, that means the newest Windows is different from the desktop-bound version that PC veterans have grown to love. But that's the point: Microsoft's vision for Windows Phones and PCs calls for a different type of userone with phone and tablet in hand, always in the cloud.
Finally, Windows 8 and Windows Phone 8 provide some reasons for users to go all-in.
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