Froyo isn't available for most Android phones yet, but that doesn't mean that you can't get it on your HTC HD2! We've already shown you a couple of versions of Android running on the HD2 (like the Nexus One and Desire ROMs), but this takes the cake as perhaps the best implementation yet. With Froyo you get a boost in speed, plus nearly everything works including the phone, WiFi, camera, and more. There are still a few bugs, plus battery life isn't great, so you probably wouldn't want to run this full time.
Here's the How To:
1. Download the files (torrent link)
2. Extract the files to your storage card
3. Run CLRCAD.exe to get the audio to work
4. Run Haret.exe and wait three minutes
5. To get back to Windows Mobile, soft reset
For more info, check out the thread on XDA.
(Thanks for the tip, stirkac)