Microsoft has announced that its brand new mobile operating system, Windows Phone 7, has gone gold and has been released to manufacturers (RTM). Windows Phone 7, the successor to Windows Mobile 6.5, is now rolling out to various manufacturers and carriers across the world, where last minute tweaks and modifications will be carried out. There's no precise date set yet, but the OS is currently scheduled for public release sometime in October. Engadget have an in-depth preview of Windows Phone 7 if you want further information on the software, which is packed full of great new features. The question is however, will it be enough to challenge Apple's supremacy in the smartphone market?