After a couple of delays, Microsoft finally has made available to the public the Windows Phone 8 software development kit (SDK) -- a day after launching its next-generation smartphone platform.
Microsoft made the SDK, along with a free version of Visual Studio Express 2012 and Blend 5, available to MSDN subscribers and to the public for download on October 30.
The public Windows Phone 8 SDK is available for download from Microsoft's Web site. The MSDN version of Windows Phone 8 SDK is here.
Microsoft made the announcement at its Build 2012 developer conference, which kicked off in Redmond at Microsoft headquarters, on October 30. The Day 1 keynote headliner was CEO Steve Ballmer, who actually did his own demos and accessed his own real accounts on stage as part of his address.
Ballmer announced that since Windows 8 became generally available on October 26, Microsoft has sold four million upgrade copies of the operating system. (This number doesn't include any additional sales of Windows 8 that is preloaded on new PCs.)
Ballmer and other Microsoft execs also announced coming availability of more Windows 8 apps, including a new Twitter client being developed by Twitter itself. This client will be out sometime in "the coming months," Ballmer said. Other developers who have committed to new Windows 8 apps, as announced today, include SAP, Dropbox and ESPN.
On the Windows Phone 8 front, Microsoft has angered a number of its existing phone developers by holding off on releasing publicly the SDK until so late in the development cycle. Microsoft officials had said the reason for waiting to make the SDK public was because going earlier would tip Microsoft's hand on a number of key, unannounced phone features. However, at the Windows Phone 8 launch -- which took place in San Francisco on October 29 -- Microsoft didn't release many (if any) unexpected big features that seemingly would merit the delay.
The good news is that Windows Phone 8 can run Windows Phone 7.X apps. But unless developers were among the chosen few who got early access to the SDK, they haven't been able to build apps that take advantage of the new Windows Phone 8 features, like NFC, Wallet, and multicore until today.
At Build, Microsoft and Nokia announced give-aways for the paying attendees. Those who made the trek to Redmond are getting 100 GB of SkyDrive storage for free, a 32 GB Surface RT with a touch cover and a Nokia Lumia 920.
This item first appeared on ZDNet's All About Microsoft blog under the headline "Microsoft delivers Windows Phone 8 software development kit."