Developers at xda-developers forum has just managed to extract the Windows Mobile 7 (WP7) Build 7.0.0.6077 which is ripped out of the official PC Emulator software, that Microsoft released yesterday at MIX10 along with other development tools.
As the leaked build has been ripped from the emulator and not from Windows Phone 7 Series, it will be difficult to make a working ROM out of leaked build. There are speculations whether a Windows Phone 7 ROM can be loaded on an existing Windows Mobile series or not. It is important to note that the leaked version of build 7.0.0.6077 of Windows Phone 7 cannot be ported to any devices and will work only on Windows PC.
Download Windows Mobile 7 Leaked ROM
Windows 7 (WP7) Build 7.0.0.6077
Catch the development on the leaked ROM of Windows 7 by on this thread.