We reported a couple of days ago a new rom that allows you to have Windows 7 on our phone HD2 to receive updates and official Microsoft simply with the Zune software.
For those who want to try this fantastic new rom, I myself have made on our forum a complete and detailed step by step guide. Some users have already tested and successfully installed Windows Phone 7. For questions or further information, if interested, you can click here in the room [Guide] How to install the rom WP7 "Back to the Future" 7720