Unlike what Microsoft originally promised, Windows Phone 8 software development kit (SDK) will now be available later this year.

The estimated time of delivery for Windows Phone 8 SDK was this summer season, but now, the full SDK will be available when Microsoft launches Windows Phone 8. Coming next week, Microsoft will “share detailed instructions on how current Windows Phone developers with published apps can apply to obtain the near-final Windows Phone 8 SDK”. A limited number of developers will get the SDK, until the Windows Phone 8 does not release in public.

So far, the private builds of Windows Phone 8 SDK is available to a small number of developers outside the company. It is believed that the full version SDK will be based on the several significant changes done in Windows Phone 8, as compared to the current 7.x version. Windows Phone 8 operating system will include several brand-new features, like multicore support, NFC support, and encryption. And based on that, developers will be able to leverage the SDK. But of course, Microsoft is guaranteeing that Windows Phone 7.x apps will run on Windows Phone 8.

While Microsoft is set to officially launch Windows 8 on October 26, we just saw an unlocked Nokia Lumia 920 surfacing up that runs on Windows Phone 8 OS. It comes some amazing features like 4.5-inch Nokia PureMotion HD Plus display, 8-megapixel rear-facing camera, built-in wireless charging, NF, and Tap+Share. You can find the complete Nokia Lumia 920 review here.

Windows 8 is a big part of Microsoft’s bid to become a big part of future tablets, so a delay in the ability for developers to make apps for those will slow down adoption and reasons to buy into it as the new tablet OS.

As Windows 8 will publicly launch, a flood of devices running on this Windows 8 OS is expected. Besides Windows 8 and Windows 8 PCs coming out, the Microsoft Surface Windows RT and Windows Pro tablets will also debut. Almost all major mobile manufacturers; Samsung, Sony, Asus, and HP have announced their devices that will run on this much—anticipated OS.

[Image credit: CBS Interactive, 2012]