Windows 7 Series Phopne are Available on near About Christimas 2010, but before 8 Month XDA developers have acquired a code dump of the Windows Phone 7 operating system. The code was pulled from the SDK emulator image and currently only runs on an x86 PC, but the XDA gang is already starting to prod and dissect the code in anticipation of a full ROM.
You can Download the Windows Phone 7 build 7.0.0.6077 ROM from here
