Microsoft has just announced Cortana, a new voice search tool for Windows Phone 8.1. Powered by Bing, it will eventually replace the search function in Windows Phone, and you'll be able to access it (her?) through a special Live Tile. On top of search, it can make calls, send texts, take notes, give reminders and set alarms. Microsoft also said that it'll work with third-party apps, and that it's already been working with select developers like Hulu and Facebook. To show that Cortana isn't just vaporware, despite its beta status, Windows Phone manager Joe Belfiore ran through a demo at Build 2014 -- more details after the break.