Putting the Nexus One aside and shelving the Nexus S as not a real developer phone, and what’s left, the mecca of developer phones the HTC HD2. The HD2 has seen many versions of Android and of course WP6.5 and WP7 (it ships with 6.5) now if you’re the modding type you’ve got two more choices.
Cyanogen Mod 7
Although it’s not in it’s final release Cyanogen Mod 7 or CM7 for short is capable of running on the HD2 as seen by the picture above from pocketnow. Cyanogen and Team Douche build the Cyanogen Mods with a framework approach whereby developers can “plug in” the files necessary for the hardware they want to run it on giving Cyanogen Mod the widest variety of handsets to work on.
Although CM7 isn’t in it’s final release yet, it’s darn close head over here for more info
UPDATE: We’ve been informed by twitter users @motomudder and @six6sicks that the CM7 is not in full release (as it says several times above and that the thread is locked)
Then over at XDA the developers have been able to get the HD2 to dual boot either WP7 or Android. Because of a proprietary formatting of the SD card with Windows Phone 7 two SD cards are necessary for this dual boot so it’s kind of sort of not a true dual boot but amazing nonetheless.
If you’re more of a Windows Phone 7 and Android person head over here to XDA to read up on this dual boot