Microsoft just revealed Windows Phone 8 will be released this fall as the next version of its mobile phone operating system. Further details are coming at the Windows Phone 8 Platform Preview, which is underway right now. The biggest change is under the hood: the OS now has a "shared core" with Windows 8.

There's other news as well: Windows Phone 8 will support dual-core CPUs on day one (and quad-cores in the future), and will also offer three screen resolutions, maxing out at 1280 x 768. Windows Phone 8 will also finally bring real support for microSD cards, and Microsoft says apps developed for 7.5 will not require refactoring for the new resolutions.

Additionally, Internet Explorer 10 will be built into the OS, and its rendering engine will mirror the desktop version. Microsoft will also allow native code development for the platform, meaning ports of graphic-intensive apps like games should be far less painful thanks to DirectX support. The default maps application in Windows Phone 8 will be Nokia Maps, complete with offline maps and turn-by-turn navigation "in many countries around the world."

There's also a new wallet / NFC feature — every Windows Phone will include the Wallet hub, and payments are integrated with carrier payment systems so it won't be cut out. Wallet will first launch with Orange in France, and Microsoft says it's working with the Isis consortium in the US to bring Wallet to AT&T, Verizon, and T-Mobile next year. Microsoft is also adding in-app purchasing to Windows Phone apps, tied into the Wallet.

Microsoft also says Windows Phone 8 is "ready for business" with encryption and secure boot features. IT admins can also set up their own app deployment strategies and enable device management tools that also work with Windows PCs. "The shared core has really played a huge role in making Windows Phone great for businesses," said Microsoft's Joe Belfiore.

Lastly, Windows Phone 8 has a new start screen with resizable tiles — double-wide, regular, and small. Any tile can be set to any of the three sizes, and they'll keep updating live. The small tiles are pretty small; lots of information can be packed onto the homescreen now.

For more, check out our complete preview of Windows Phone 8 with in-depth analysis of all the new features.