Microsoft's Windows Phone 8.1 was announced less than two weeks ago, but Microsoft is already releasing this version of its mobile operating system to developers. Microsoft today announced that registered developers will have access to Windows Phone Preview for Developers, which will offer pre-release Windows Phone OS updates for development devices. The app will let developers test and validate their apps on a real device before the update hits general availability.
If you're not already registered as a developer, you'll need to either register as a Windows Phone Developer (this costs $19 and allows you to publish apps in the Microsoft Store), register as a dev with App Studio (free, and you can create your own apps), or developer unlock your phone using the developer tools.
The biggest addition with Windows Phone 8.1 is Cortana, Microsoft's answer to Google Now and Apple's Siri. This virtual assistant will help you set reminders, find your way around town, and answer questions via search engine results. There's also Internet Explorer 11 (with WebGL), a new YouTube player with support for HTML5 video, Battery Sense for tracking battery usage, Storage Sense for moving and organizing apps and files, WiFi Sense for managing connections, improvements to multitasking, a third row of Live Tiles regardless of screen size, Twitter integration on the Contacts Hub, and streaming via Xbox Music and Xbox Video.