Rumors have been circulating for a while that Microsoft is planning to incorporate its personal digital assistant, Cortana, into the next major version of Windows. On August 11, those rumors turned up a notch, with Neowin.net reporting that internal "dogfood" builds of "Threshold," aka Windows 9, include Cortana integration. Windows Threshold is expected to arrive in the spring of 2015. A public preview of Threshold may be available this fall, according to my sources. As is the case with Cortana on Windows Phone 8.1, Cortana will be an app, not part of the operating system itself, Neowin's Brad Sams said. Cortana takes its codename from Cortana, an artifically intelligent character in Microsoft's Halo series who can learn and adapt. Cortana relies on machine-learning technology and the "Satori" knowledge repository powering Bing to learn what users want to find, track and do.