Good to know, that there isn't a working build yet.
Users in some other boards wrote, that there is an early build with limited functionality. But this might be not the truth. I think xda-developers are more believable.
I think I should wait a while, because the first WP7 devices aren't released long time ago. Hacking the OS might be much easier while having devices running WP7.
Maybe someone write here, if there is a working HD2 build of WP7, that would be very great