This is not the first time I heard about this rumor (cannot reveal source). It seems that another source has also received the same information that HTC HD2 is getting Windows Mobile 7. It seems that HTC HD2 has quality the basic requirement for Windows Mobile 7. Therefore, when Windows Mobile is to be released next year, it is one of the candidate for it. Finger crossed that this rumor is true. 🙂
(source)