Microsoft recently shared that their voice and search assistant which they lovingly named Cortana (after the Halo game's AI character) will be available in a beta format for Android as early as July of this year. Windows 10, which is being released July 29th of this year will include Cortana baked into the OS. The fact that Microsoft is porting her to other systems reinforces their new focus on spreading the love of Microsoft products around to other platforms.
Microsoft clarified that the Android app beta of Cortana will be "working as a companion to Cortana on your Windows 10 PC." They did not clarify what that actually means for the software. This leaves the question as to whether Cortana for Android will end up as a stripped down version unworthy of the Windows 10 original, or if it will come with most of her full functionality.
For the most part, Microsoft's description indicates that Cortana for Android will work similarly to what is already found in Siri and Google Now. The one advantage of Cortana seems to be that her interactive speech patterns are superior to what Apple and Google offer.
Incidentally, this news comes along with a story about Cortana coming to the Xbox One. Check out the Microsoft source link below for more details. The above video is a demo of the Phone Companion App for Windows 10.
Source: Microsoft