During the Windows Phone Summit, Microsoft announced that Windows Phone 8 will support three screen resolutions insted of the only one supported by Windows Phone 7.5.
Windows Phone 8 will have three screen resolutions: WVGA, WXGA and 720p.
The three screen resolutions supported in Windows Phone 8 will have similar aspect ratios.
“A developer doesn’t need to do anything to take advantage of the new screen resolutions,” Microsoft’s representative said. “We will automatically scale all of the assets of the application appropriately.” App developers will have the opportunity to optimize their apps with higher resolution imagery and additional assets, but they won’t have to.” He added.
Earlier they were planning to add a resolution of 640×480 but they dropped the idea because it would have created issues for the developers as they would have to rewrite their apps for two aspect ratios, one for 15:9 and other for 16:9 which would have led to a lot of problems.